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• Windows DNS Server 2008 R2 fallaciously returns SERVFAIL

  - by Easter Sunshine

  I have a Windows 2008 R2 domain controller which is also a DNS server. When resolving certain TLDs, it returns a SERVFAIL: $ dig bogus. ; <<>> DiG 9.8.1 <<>> bogus. ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 31919 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;bogus. IN A I get the same result for a real TLD like com. when querying the DC as shown above. Compare to a BIND server that is working as expected: $ dig bogus. @128.59.59.70 ; <<>> DiG 9.8.1 <<>> bogus. @128.59.59.70 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 30141 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0 ;; QUESTION SECTION: ;bogus. IN A ;; AUTHORITY SECTION: . 10800 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2012012501 1800 900 604800 86400 ;; Query time: 18 msec ;; SERVER: 128.59.59.70#53(128.59.59.70) ;; WHEN: Wed Jan 25 14:09:14 2012 ;; MSG SIZE rcvd: 98 Similarly, when I query my Windows DNS server with dig . any, I get a SERVFAIL but the BIND servers return the root zone as expected. This sounds similar to the issue described in http://support.microsoft.com/kb/968372 except I am using two forwarders (128.59.59.70 from above as well as 128.59.62.10) and falling back to root hints so the preconditions to expose the issue are not the same. Nevertheless, I also applied the MaxCacheTTL registry fix as described and restarted DNS and the whole server as well but the problem persists. The problem occurs on all domain controllers in this domain and has occurred since half a year ago, even though the servers are getting automatic Windows updates. EDIT Here is a debug log. The client is 160.39.114.110, which is my workstation. 1/25/2012 2:16:01 PM 0E08 PACKET 000000001EA6BFD0 UDP Rcv 160.39.114.110 2e94 Q [0001 D NOERROR] A (5)bogus(0) UDP question info at 000000001EA6BFD0 Socket = 508 Remote addr 160.39.114.110, port 49710 Time Query=1077016, Queued=0, Expire=0 Buf length = 0x0fa0 (4000) Msg length = 0x0017 (23) Message: XID 0x2e94 Flags 0x0100 QR 0 (QUESTION) OPCODE 0 (QUERY) AA 0 TC 0 RD 1 RA 0 Z 0 CD 0 AD 0 RCODE 0 (NOERROR) QCOUNT 1 ACOUNT 0 NSCOUNT 0 ARCOUNT 0 QUESTION SECTION: Offset = 0x000c, RR count = 0 Name "(5)bogus(0)" QTYPE A (1) QCLASS 1 ANSWER SECTION: empty AUTHORITY SECTION: empty ADDITIONAL SECTION: empty 1/25/2012 2:16:01 PM 0E08 PACKET 000000001EA6BFD0 UDP Snd 160.39.114.110 2e94 R Q [8281 DR SERVFAIL] A (5)bogus(0) UDP response info at 000000001EA6BFD0 Socket = 508 Remote addr 160.39.114.110, port 49710 Time Query=1077016, Queued=0, Expire=0 Buf length = 0x0fa0 (4000) Msg length = 0x0017 (23) Message: XID 0x2e94 Flags 0x8182 QR 1 (RESPONSE) OPCODE 0 (QUERY) AA 0 TC 0 RD 1 RA 1 Z 0 CD 0 AD 0 RCODE 2 (SERVFAIL) QCOUNT 1 ACOUNT 0 NSCOUNT 0 ARCOUNT 0 QUESTION SECTION: Offset = 0x000c, RR count = 0 Name "(5)bogus(0)" QTYPE A (1) QCLASS 1 ANSWER SECTION: empty AUTHORITY SECTION: empty ADDITIONAL SECTION: empty Every option in the debug log box was checked except "filter by IP". By contrast, when I query, say, accounts.google.com, I can see the DNS server go out to its forwarder (128.59.59.70, for example). In this case, I didn't see any packets going out from my DNS server even though bogus. was not in the cache (the debug log was already running and this is the first time I queried this server for bogus. or any TLD). It just returned SERVFAIL without consulting any other DNS server, as in the Microsoft KB article linked above.

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• Inheritance Mapping Strategies with Entity Framework Code First CTP5: Part 2 – Table per Type (TPT)

  - by mortezam

  In the previous blog post you saw that there are three different approaches to representing an inheritance hierarchy and I explained Table per Hierarchy (TPH) as the default mapping strategy in EF Code First. We argued that the disadvantages of TPH may be too serious for our design since it results in denormalized schemas that can become a major burden in the long run. In today’s blog post we are going to learn about Table per Type (TPT) as another inheritance mapping strategy and we'll see that TPT doesn’t expose us to this problem. Table per Type (TPT)Table per Type is about representing inheritance relationships as relational foreign key associations. Every class/subclass that declares persistent properties—including abstract classes—has its own table. The table for subclasses contains columns only for each noninherited property (each property declared by the subclass itself) along with a primary key that is also a foreign key of the base class table. This approach is shown in the following figure: For example, if an instance of the CreditCard subclass is made persistent, the values of properties declared by the BillingDetail base class are persisted to a new row of the BillingDetails table. Only the values of properties declared by the subclass (i.e. CreditCard) are persisted to a new row of the CreditCards table. The two rows are linked together by their shared primary key value. Later, the subclass instance may be retrieved from the database by joining the subclass table with the base class table. TPT Advantages The primary advantage of this strategy is that the SQL schema is normalized. In addition, schema evolution is straightforward (modifying the base class or adding a new subclass is just a matter of modify/add one table). Integrity constraint definition are also straightforward (note how CardType in CreditCards table is now a non-nullable column). Another much more important advantage is the ability to handle polymorphic associations (a polymorphic association is an association to a base class, hence to all classes in the hierarchy with dynamic resolution of the concrete class at runtime). A polymorphic association to a particular subclass may be represented as a foreign key referencing the table of that particular subclass. Implement TPT in EF Code First We can create a TPT mapping simply by placing Table attribute on the subclasses to specify the mapped table name (Table attribute is a new data annotation and has been added to System.ComponentModel.DataAnnotations namespace in CTP5): public abstract class BillingDetail {     public int BillingDetailId { get; set; }     public string Owner { get; set; }     public string Number { get; set; } } [Table("BankAccounts")] public class BankAccount : BillingDetail {     public string BankName { get; set; }     public string Swift { get; set; } } [Table("CreditCards")] public class CreditCard : BillingDetail {     public int CardType { get; set; }     public string ExpiryMonth { get; set; }     public string ExpiryYear { get; set; } } public class InheritanceMappingContext : DbContext {     public DbSet<BillingDetail> BillingDetails { get; set; } } If you prefer fluent API, then you can create a TPT mapping by using ToTable() method: protected override void OnModelCreating(ModelBuilder modelBuilder) {     modelBuilder.Entity<BankAccount>().ToTable("BankAccounts");     modelBuilder.Entity<CreditCard>().ToTable("CreditCards"); } Generated SQL For QueriesLet’s take an example of a simple non-polymorphic query that returns a list of all the BankAccounts: var query = from b in context.BillingDetails.OfType<BankAccount>() select b; Executing this query (by invoking ToList() method) results in the following SQL statements being sent to the database (on the bottom, you can also see the result of executing the generated query in SQL Server Management Studio): Now, let’s take an example of a very simple polymorphic query that requests all the BillingDetails which includes both BankAccount and CreditCard types: projects some properties out of the base class BillingDetail, without querying for anything from any of the subclasses: var query = from b in context.BillingDetails             select new { b.BillingDetailId, b.Number, b.Owner }; -- var query = from b in context.BillingDetails select b; This LINQ query seems even more simple than the previous one but the resulting SQL query is not as simple as you might expect: -- As you can see, EF Code First relies on an INNER JOIN to detect the existence (or absence) of rows in the subclass tables CreditCards and BankAccounts so it can determine the concrete subclass for a particular row of the BillingDetails table. Also the SQL CASE statements that you see in the beginning of the query is just to ensure columns that are irrelevant for a particular row have NULL values in the returning flattened table. (e.g. BankName for a row that represents a CreditCard type) TPT ConsiderationsEven though this mapping strategy is deceptively simple, the experience shows that performance can be unacceptable for complex class hierarchies because queries always require a join across many tables. In addition, this mapping strategy is more difficult to implement by hand— even ad-hoc reporting is more complex. This is an important consideration if you plan to use handwritten SQL in your application (For ad hoc reporting, database views provide a way to offset the complexity of the TPT strategy. A view may be used to transform the table-per-type model into the much simpler table-per-hierarchy model.) SummaryIn this post we learned about Table per Type as the second inheritance mapping in our series. So far, the strategies we’ve discussed require extra consideration with regard to the SQL schema (e.g. in TPT, foreign keys are needed). This situation changes with the Table per Concrete Type (TPC) that we will discuss in the next post. References ADO.NET team blog Java Persistence with Hibernate book a { text-decoration: none; } a:visited { color: Blue; } .title { padding-bottom: 5px; font-family: Segoe UI; font-size: 11pt; font-weight: bold; padding-top: 15px; } .code, .typeName { font-family: consolas; } .typeName { color: #2b91af; } .padTop5 { padding-top: 5px; } .padTop10 { padding-top: 10px; } p.MsoNormal { margin-top: 0in; margin-right: 0in; margin-bottom: 10.0pt; margin-left: 0in; line-height: 115%; font-size: 11.0pt; font-family: "Calibri" , "sans-serif"; }

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• How do I add a column that displays the number of distinct rows to this query?

  - by Fake Code Monkey Rashid

  Hello good people! I don't know how to ask my question clearly so I'll just show you the money. To start with, here's a sample table: CREATE TABLE sandbox ( id integer NOT NULL, callsign text NOT NULL, this text NOT NULL, that text NOT NULL, "timestamp" timestamp with time zone DEFAULT now() NOT NULL ); CREATE SEQUENCE sandbox_id_seq START WITH 1 INCREMENT BY 1 NO MINVALUE NO MAXVALUE CACHE 1; ALTER SEQUENCE sandbox_id_seq OWNED BY sandbox.id; SELECT pg_catalog.setval('sandbox_id_seq', 14, true); ALTER TABLE sandbox ALTER COLUMN id SET DEFAULT nextval('sandbox_id_seq'::regclass); INSERT INTO sandbox VALUES (1, 'alpha', 'foo', 'qux', '2010-12-29 16:51:09.897579+00'); INSERT INTO sandbox VALUES (2, 'alpha', 'foo', 'qux', '2010-12-29 16:51:36.108867+00'); INSERT INTO sandbox VALUES (3, 'bravo', 'bar', 'quxx', '2010-12-29 16:52:36.370507+00'); INSERT INTO sandbox VALUES (4, 'bravo', 'foo', 'quxx', '2010-12-29 16:52:47.584663+00'); INSERT INTO sandbox VALUES (5, 'charlie', 'foo', 'corge', '2010-12-29 16:53:00.742356+00'); INSERT INTO sandbox VALUES (6, 'delta', 'foo', 'qux', '2010-12-29 16:53:10.884721+00'); INSERT INTO sandbox VALUES (7, 'alpha', 'foo', 'corge', '2010-12-29 16:53:21.242904+00'); INSERT INTO sandbox VALUES (8, 'alpha', 'bar', 'corge', '2010-12-29 16:54:33.318907+00'); INSERT INTO sandbox VALUES (9, 'alpha', 'baz', 'quxx', '2010-12-29 16:54:38.727095+00'); INSERT INTO sandbox VALUES (10, 'alpha', 'bar', 'qux', '2010-12-29 16:54:46.237294+00'); INSERT INTO sandbox VALUES (11, 'alpha', 'baz', 'qux', '2010-12-29 16:54:53.891606+00'); INSERT INTO sandbox VALUES (12, 'alpha', 'baz', 'corge', '2010-12-29 16:55:39.596076+00'); INSERT INTO sandbox VALUES (13, 'alpha', 'baz', 'corge', '2010-12-29 16:55:44.834019+00'); INSERT INTO sandbox VALUES (14, 'alpha', 'foo', 'qux', '2010-12-29 16:55:52.848792+00'); ALTER TABLE ONLY sandbox ADD CONSTRAINT sandbox_pkey PRIMARY KEY (id); Here's the current SQL query I have: SELECT * FROM ( SELECT DISTINCT ON (this, that) id, this, that, timestamp FROM sandbox WHERE callsign = 'alpha' AND CAST(timestamp AS date) = '2010-12-29' ) playground ORDER BY timestamp DESC This is the result it gives me: id this that timestamp ----------------------------------------------------- 14 foo qux 2010-12-29 16:55:52.848792+00 13 baz corge 2010-12-29 16:55:44.834019+00 11 baz qux 2010-12-29 16:54:53.891606+00 10 bar qux 2010-12-29 16:54:46.237294+00 9 baz quxx 2010-12-29 16:54:38.727095+00 8 bar corge 2010-12-29 16:54:33.318907+00 7 foo corge 2010-12-29 16:53:21.242904+00 This is what I want to see: id this that timestamp count ------------------------------------------------------------- 14 foo qux 2010-12-29 16:55:52.848792+00 3 13 baz corge 2010-12-29 16:55:44.834019+00 2 11 baz qux 2010-12-29 16:54:53.891606+00 1 10 bar qux 2010-12-29 16:54:46.237294+00 1 9 baz quxx 2010-12-29 16:54:38.727095+00 1 8 bar corge 2010-12-29 16:54:33.318907+00 1 7 foo corge 2010-12-29 16:53:21.242904+00 1 EDIT: I'm using PostgreSQL 9.0.* (if that helps any).

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• How can you make an emacs macro wait for cscope query results?

  - by Sudhanshu

  I am trying to write a macro which calls cscope-find-functions-calling-this-function on each and every tag in a file displayed in the *Tags List* buffer (created by list-tags command). This should create a buffer which contains list of all functions calling a set of functions defined in a certain file. This is the sequence of keystrokes: 1. <f11> ;; cscope-find-functions-calling-this-function 2. RET ;; newline [shows results of cscope in a split window] 3. C-x C-p ;; mark-page 4. C-x C-x ;; icicle-exchange-point-and-mark 5. <up> ;; previous-line 6. <end> ;; end-of-line [region to copy has been marked] 7. <f7> ;; append-results-to-buffer 8. C-x ESC O ;; [move back to split window on the right] 9. C-x b ;; icicle-buffer [Switch back to *Tags List* buffer] 10. *Tags ;; self-insert-command * 5 11. SPC ;; self-insert-command 12. List* ;; self-insert-command * 5 13. RET ;; newline 14 . <down> ;; next-line [Position point on next tag in the list] Problem: I get no results in the buffer, and I found out that's because Step 3-7 execute even before cscope prints the results of query made on Steps 1-2. I can insert a pause in the macro by using C-x q, but I'd rather like the macro to wait after Step 2, until cscope has returned with the results and only then continue further. I suspect this is not possible through a macro, maybe a LISP function... I'm not a lisp expert myself. Can someone please help? Thanks! Details: I have Icicles installed so by default I get word at point in current buffer as input in minibuffer. F11 is bound to cscope-find-functions-calling-this-function windmove is installed and C-x (C-x ESC o - as shown below) takes you to the right window. F7 is bound to append-results-to-buffer which is defined as: (defun append-results-to-buffer () (interactive) (append-to-buffer (get-buffer-create "c1") (point) (mark))) This function just appends the currently marked region to a buffer named "c1".

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• How can I iterate over a collection of objects returned by a LINQ-to-XML query?

  - by billmaya

  I've got this XML: <BillingLog> <BillingItem> <date-and-time>2003-11-04</date-and-time> <application-name>Billing Service</application-name> <severity>Warning</severity> <process-id>123</process-id> <description>Timed out on a connection</description> <detail>Timed out after three retries.</detail> </BillingItem> <BillingItem> <date-and-time>2010-05-15</date-and-time> <application-name>Callback Service</application-name> <severity>Error</severity> <process-id>456</process-id> <description>Unable to process callback</description> <detail>Reconciliation timed out after two retries.</detail> </BillingItem> </BillingLog> That I want to project using LINQ-to-XML into a collection of BillingItem objects contained in a single BillingLog object. public class BillingLog { public IEnumerable<BillingItem> items { get; set; } } public class BillingItem { public string Date { get; set; } public string ApplicationName { get; set; } public string Severity { get; set; } public int ProcessId { get; set; } public string Description { get; set; } public string Detail { get; set;} } This is the LINQ query that I'm using to project the XML (which is contained in the string variable source). XDocument xdoc = XDocument.Parse(source); var log = from i in xdoc.Elements("BillingLog") select new BillingLog { items = from j in i.Descendants("BillingItem") select new BillingItem { Date = (string)j.Element("date-and-time"), ApplicationName = (string)j.Element("application-name"), Severity = (string)j.Element("severity"), ProcessId = (int)j.Element("process-id"), Description = (string)j.Element("description"), Detail = (string)j.Element("detail") } }; When I try and iterate over the objects in log using foreach. foreach (BillingItem item in log) { Console.WriteLine ("{0} | {1} | {2} | {3} | {4} | {5}", item.Date, item.ApplicationName, item.Severity, item.ProcessId.ToString(), item.Description, item.Detail); } I get the following error message from LINQPad. Cannot convert type 'UserQuery.BillingLog' to 'UserQuery.BillingItem' Thanks in advance.

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• Look over my C# SQLite Query, what am I doing wrong?

  - by CODe

  I'm writing a WinForms database application using SQLite and C#. I have a sqlite query that is failing, and I'm unsure as to where I'm going wrong, as I've tried everything I could think of. public DataTable searchSubs(String businessName, String contactName) { string SQL = null; if ((businessName != null && businessName != "") && (contactName != null && contactName != "")) { // provided business name and contact name for search SQL = "SELECT * FROM SUBCONTRACTOR WHERE BusinessName LIKE %@BusinessName% AND Contact LIKE %@ContactName%"; } else if ((businessName != null && businessName != "") && (contactName == null || contactName == "")) { // provided business name only for search SQL = "SELECT * FROM SUBCONTRACTOR WHERE BusinessName LIKE %@BusinessName%"; } else if ((businessName == null || businessName == "") && (contactName != null && contactName != "")) { // provided contact name only for search SQL = "SELECT * FROM SUBCONTRACTOR WHERE Contact LIKE %@ContactName%"; } else if ((businessName == null || businessName == "") && (contactName == null || contactName == "")) { // provided no search information SQL = "SELECT * FROM SUBCONTRACTOR"; } SQLiteCommand cmd = new SQLiteCommand(SQL); cmd.Parameters.AddWithValue("@BusinessName", businessName); cmd.Parameters.AddWithValue("@ContactName", contactName); cmd.Connection = connection; SQLiteDataAdapter da = new SQLiteDataAdapter(cmd); DataSet ds = new DataSet(); try { da.Fill(ds); DataTable dt = ds.Tables[0]; return dt; } catch (Exception e) { MessageBox.Show(e.ToString()); return null; } finally { cmd.Dispose(); connection.Close(); } } I continually get an error saying that it is failing near the %'s. That's all fine and dandy, but I guess I'm structuring it wrong, but I don't know where! I tried adding apostrophes around the "like" variables, like this: SQL = "SELECT * FROM SUBCONTRACTOR WHERE Contact LIKE '%@ContactName%'"; and quite honestly, that is all I can think of. Anyone have any ideas?

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• How to query across many-to-many association in NHibernate?

  - by Splash

  I have two entities, Post and Tag. The Post entity has a collection of Tags which represents a many-to-many join between the two (that is, each post can have any number of tags and each tag can be associated with any number of posts). I am trying to retrieve all Posts which have a given tag. However, I seem to be unable to get this query right. I essentially want something which means the same as the following pseudo-HQL: from Posts p where p.Tags contains (from Tags t where t.Name = :tagName) order by p.DateTime The only thing I've found which even approaches this is a post by Ayende. However, his approach requires the entity on the other side (in my case, Tag) to have a collection showing the other end of the many-to-many. I don't have this and don't really wish to have it. I find it hard to believe this can't be done. What am I missing? My entities & mappings look like this (simplified): public class Post { public virtual int Id { get; set; } public virtual string Title { get; set; } private IList<Tag> tags = new List<Tag>(); public virtual IEnumerable<Tag> Tags { get { return tags; } } public virtual void AddTag(Tag tag) { this.tags.Add(tag); } } public class PostMap : ClassMap<Post> { public PostMap() { Id(x => x.Id).GeneratedBy.HiLo("99"); Map(x => x.Title); HasManyToMany(x => x.Tags); } } // ---- public class Tag { public virtual int Id { get; set; } public virtual string Name { get; set; } } public class TagMap : ClassMap<Tag> { public TagMap () { Id(x => x.Id).GeneratedBy.HiLo("99"); Map(x => x.Name).Unique(); } }

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• How to reflect over T to build an expression tree for a query?

  - by Alex

  Hi all, I'm trying to build a generic class to work with entities from EF. This class talks to repositories, but it's this class that creates the expressions sent to the repositories. Anyway, I'm just trying to implement one virtual method that will act as a base for common querying. Specifically, it will accept a an int and it only needs to perform a query over the primary key of the entity in question. I've been screwing around with it and I've built a reflection which may or may not work. I say that because I get a NotSupportedException with a message of LINQ to Entities does not recognize the method 'System.Object GetValue(System.Object, System.Object[])' method, and this method cannot be translated into a store expression. So then I tried another approach and it produced the same exception but with the error of The LINQ expression node type 'ArrayIndex' is not supported in LINQ to Entities. I know it's because EF will not parse the expression the way L2S will. Anyway, I'm hopping someone with a bit more experience can point me into the right direction on this. I'm posting the entire class with both attempts I've made. public class Provider<T> where T : class { protected readonly Repository<T> Repository = null; private readonly string TEntityName = typeof(T).Name; [Inject] public Provider( Repository<T> Repository) { this.Repository = Repository; } public virtual void Add( T TEntity) { this.Repository.Insert(TEntity); } public virtual T Get( int PrimaryKey) { // The LINQ expression node type 'ArrayIndex' is not supported in // LINQ to Entities. return this.Repository.Select( t => (((int)(t as EntityObject).EntityKey.EntityKeyValues[0].Value) == PrimaryKey)).Single(); // LINQ to Entities does not recognize the method // 'System.Object GetValue(System.Object, System.Object[])' method, // and this method cannot be translated into a store expression. return this.Repository.Select( t => (((int)t.GetType().GetProperties().Single( p => (p.Name == (this.TEntityName + "Id"))).GetValue(t, null)) == PrimaryKey)).Single(); } public virtual IList<T> GetAll() { return this.Repository.Select().ToList(); } protected virtual void Save() { this.Repository.Update(); } }

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• Adding to database. No repeat on refresh

  - by kevstarlive

  I have this code: Episode.php <?$feedback = new feedback; $articles = $feedback->fetch_all(); if (isset($_POST['name'], $_POST['post'])) { $cast = $_GET['id']; $name = $_POST['name']; $email = $_POST['email']; $post = nl2br ($_POST['post']); $ipaddress = $_SERVER['REMOTE_ADDR']; if (empty($name) or empty($post)) { $error = 'All Fields Are Required!'; }else{ $query = $pdo->prepare('INSERT INTO comments (cast, name, email, post, ipaddress) VALUES(?, ?, ?, ?, ?)'); $query->bindValue(1, $cast); $query->bindValue(2, $name); $query->bindValue(3, $email); $query->bindValue(4, $post); $query->bindValue(5, $ipaddress); $query->execute(); } }?> <div align="center"> <strong>Give us your feedback?</strong><br /><br /> <?php if (isset($error)) { ?> <small style="color:#aa0000;"><?php echo $error; ?></small><br /><br /> <?php } ?> <form action="episode.php?id=<?php echo $data['cast_id']; ?>" method="post" autocomplete="off" enctype="multipart/form-data"> <input type="text" name="name" placeholder="Name" /> / <input type="text" name="email" placeholder="Email" /><small style="color:#aa0000;">*</small><br /><br /> <textarea rows="10" cols="50" name="post" placeholder="Comment"></textarea><br /><br /> <input type="submit" onclick="myFunction()" value="Add Comment" /> <br /><br /> <small style="color:#aa0000;">* <b>Email will not be displayed publicly</b></small><br /> </form> </div> Include.php class feedback { public function fetch_all(){ global $pdo; $query = $pdo->prepare("SELECT * FROM comments"); $query->bindValue(1, $cast); $query->execute(); return $query->fetchAll(); } } This code updates to the database as it is suppose to. But after submission it reloads the current page as mentioned in the form action. But when I refresh the page to see the comment being added it asks to re submit. If I hit submit then the comment adds again. How can I stop this from happening? Maybe I could hide the comment box and display a thank you message but that would not stop a repeat entry. Please help. Thank you. Kev

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• Curious about IObservable? Here’s a quick example to get you started!

  - by Roman Schindlauer

  Have you heard about IObservable/IObserver support in Microsoft StreamInsight 1.1? Then you probably want to try it out. If this is your first incursion into the IObservable/IObserver pattern, this blog post is for you! StreamInsight 1.1 introduced the ability to use IEnumerable and IObservable objects as event sources and sinks. The IEnumerable case is pretty straightforward, since many data collections are already surfacing as this type. This was already covered by Colin in his blog. Creating your own IObservable event source is a little more involved but no less exciting – here is a primer: First, let’s look at a very simple Observable data source. All it does is publish an integer in regular time periods to its registered observers. (For more information on IObservable, see http://msdn.microsoft.com/en-us/library/dd990377.aspx ). sealed class RandomSubject : IObservable<int>, IDisposable {     private bool _done;     private readonly List<IObserver<int>> _observers;     private readonly Random _random;     private readonly object _sync;     private readonly Timer _timer;     private readonly int _timerPeriod;       /// <summary>     /// Random observable subject. It produces an integer in regular time periods.     /// </summary>     /// <param name="timerPeriod">Timer period (in milliseconds)</param>     public RandomSubject(int timerPeriod)     {         _done = false;         _observers = new List<IObserver<int>>();         _random = new Random();         _sync = new object();         _timer = new Timer(EmitRandomValue);         _timerPeriod = timerPeriod;         Schedule();     }       public IDisposable Subscribe(IObserver<int> observer)     {         lock (_sync)         {             _observers.Add(observer);         }         return new Subscription(this, observer);     }       public void OnNext(int value)     {         lock (_sync)         {             if (!_done)             {                 foreach (var observer in _observers)                 {                     observer.OnNext(value);                 }             }         }     }       public void OnError(Exception e)     {         lock (_sync)         {             foreach (var observer in _observers)             {                 observer.OnError(e);             }             _done = true;         }     }       public void OnCompleted()     {         lock (_sync)         {             foreach (var observer in _observers)             {                 observer.OnCompleted();             }             _done = true;         }     }       void IDisposable.Dispose()     {         _timer.Dispose();     }       private void Schedule()     {         lock (_sync)         {             if (!_done)             {                 _timer.Change(_timerPeriod, Timeout.Infinite);             }         }     }       private void EmitRandomValue(object _)     {         var value = (int)(_random.NextDouble() * 100);         Console.WriteLine("[Observable]\t" + value);         OnNext(value);         Schedule();     }       private sealed class Subscription : IDisposable     {         private readonly RandomSubject _subject;         private IObserver<int> _observer;           public Subscription(RandomSubject subject, IObserver<int> observer)         {             _subject = subject;             _observer = observer;         }           public void Dispose()         {             IObserver<int> observer = _observer;             if (null != observer)             {                 lock (_subject._sync)                 {                     _subject._observers.Remove(observer);                 }                 _observer = null;             }         }     } }   So far, so good. Now let’s write a program that consumes data emitted by the observable as a stream of point events in a Streaminsight query. First, let’s define our payload type: class Payload {     public int Value { get; set; }       public override string ToString()     {         return "[StreamInsight]\tValue: " + Value.ToString();     } }   Now, let’s write the program. First, we will instantiate the observable subject. Then we’ll use the ToPointStream() method to consume it as a stream. We can now write any query over the source - here, a simple pass-through query. class Program {     static void Main(string[] args)     {         Console.WriteLine("Starting observable source...");         using (var source = new RandomSubject(500))         {             Console.WriteLine("Started observable source.");             using (var server = Server.Create("Default"))             {                 var application = server.CreateApplication("My Application");                   var stream = source.ToPointStream(application,                     e => PointEvent.CreateInsert(DateTime.Now, new Payload { Value = e }),                     AdvanceTimeSettings.StrictlyIncreasingStartTime,                     "Observable Stream");                   var query = from e in stream                             select e;                   [...]   We’re done with consuming input and querying it! But you probably want to see the output of the query. Did you know you can turn a query into an observable subject as well? Let’s do precisely that, and exploit the Reactive Extensions for .NET (http://msdn.microsoft.com/en-us/devlabs/ee794896.aspx) to quickly visualize the output. Notice we’re subscribing “Console.WriteLine()” to the query, a pattern you may find useful for quick debugging of your queries. Reminder: you’ll need to install the Reactive Extensions for .NET (Rx for .NET Framework 4.0), and reference System.CoreEx and System.Reactive in your project.                 [...]                   Console.ReadLine();                 Console.WriteLine("Starting query...");                 using (query.ToObservable().Subscribe(Console.WriteLine))                 {                     Console.WriteLine("Started query.");                     Console.ReadLine();                     Console.WriteLine("Stopping query...");                 }                 Console.WriteLine("Stopped query.");             }             Console.ReadLine();             Console.WriteLine("Stopping observable source...");             source.OnCompleted();         }         Console.WriteLine("Stopped observable source.");     } }   We hope this blog post gets you started. And for bonus points, you can go ahead and rewrite the observable source (the RandomSubject class) using the Reactive Extensions for .NET! The entire sample project is attached to this article. Happy querying! Regards, The StreamInsight Team

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• Creating PHP Forms with show/hide functionality [migrated]

  - by ronquiq

  I want to create two reports and submit the report data to database by using two functions defined in a class: Here I have two buttons: "Create ES" and "Create RP". Rightnow, my forms are working fine, I can insert data successfully, but the problem was when I click on submit after filling the form data, the content is hiding and displays the fist div content "cs_content" and again I need to onclick to submit again. Could anyone give a solution for this. Requirement : When I click on "Create CS", I should be able to fill the form and submit data successfully with a message within "cs_content" and any form input errors, the errors should display within "cs_content". When I click on "Create RP", I should be able to fill the form and submit data successfully with a message within "rp_content" and any form input errors, the errors should display within "rp_content". home.php <?php require 'classes/class.report.php'; $report = new Report($db); ?> <html> <head> <script src="js/jqueryv1.10.2.js"></script> <script> $ (document).ready(function () { //$("#cs_content").show(); $('#cs').click(function () { $('#cs_content').fadeIn('slow'); $('#rp_content').hide(); }); $('#rp').click(function () { $('#rp_content').fadeIn('slow'); $('#cs_content').hide(); }); }); </script> </head> <body> <div class="container2"> <div style="margin:0px 0px;padding:3px 217px;overflow:hidden;"> <div id="cs" style="float:left;margin:0px 0px;padding:7px;"><input type="button" value="CREATE CS"></div> <div id="rp" style="float:left;margin:0px 0px;padding:7px;"><input type="button" value="CREATE RP"></div><br> </div> <div id="cs_content"> <?php $report->create_cs_report(); ?> </div> <div id="rp_content" style="display:none;"> <?php $report->create_rp_report(); ?> </div> </div> </body> </html> class.report.php <?php class Report { private $db; public function __construct($database){ $this->db = $database; } public function create_cs_report() { if (isset($_POST['create_es_report'])) { $report_name = htmlentities($_POST['report_name']); $from_address = htmlentities($_POST['from_address']); $subject = htmlentities($_POST['subject']); $reply_to = htmlentities($_POST['reply_to']); if (empty($_POST['report_name']) || empty($_POST['from_address']) || empty($_POST['subject']) || empty($_POST['reply_to'])) { $errors[] = '<span class="error">All fields are required.</span>'; } else { if (isset($_POST['report_name']) && empty($_POST['report_name'])) { $errors[] = '<span class="error">Report Name is required</span>'; } else if (!ctype_alnum($_POST['report_name'])) { $errors[] = '<span class="error">Report Name: Whitespace is not allowed, only alphabets and numbers are required</span>'; } if (isset($_POST['from_address']) && empty($_POST['from_address'])) { $errors[] = '<span class="error">From address is required</span>'; } else if (filter_var($_POST['from_address'], FILTER_VALIDATE_EMAIL) === false) { $errors[] = '<span class="error">Please enter a valid From address</span>'; } if (isset($_POST['subject']) && empty($_POST['subject'])) { $errors[] = '<span class="error">Subject is required</span>'; } else if (!ctype_alnum($_POST['subject'])) { $errors[] = '<span class="error">Subject: Whitespace is not allowed, only alphabets and numbers are required</span>'; } if (isset($_POST['reply_to']) && empty($_POST['reply_to'])) { $errors[] = '<span class="error">Reply To is required</span>'; } else if (filter_var($_POST['reply_to'], FILTER_VALIDATE_EMAIL) === false) { $errors[] = '<span class="error">Please enter a valid Reply-To address</span>'; } } if (empty($errors) === true) { $query = $this->db->prepare("INSERT INTO report(report_name, from_address, subject, reply_to) VALUES (?, ?, ?, ?) "); $query->bindValue(1, $report_name); $query->bindValue(2, $from_address); $query->bindValue(3, $subject); $query->bindValue(4, $reply_to); try { $query->execute(); } catch(PDOException $e) { die($e->getMessage()); } header('Location:home.php?success'); exit(); } } if (isset($_GET['success']) && empty($_GET['success'])) { header('Location:home.php'); echo '<span class="error">Report is succesfully created</span>'; } ?> <form action="" method="POST" accept-charset="UTF-8"> <div style="font-weight:bold;padding:17px 80px;text-decoration:underline;">Section A</div> <table class="create_report"> <tr><td><label>Report Name</label><span style="color:#A60000">*</span></td> <td><input type="text" name="report_name" required placeholder="Name of the report" value="<?php if(isset($_POST["report_name"])) echo $report_name; ?>" size="30" maxlength="30"> </td></tr> <tr><td><label>From</label><span style="color:#A60000">*</span></td> <td><input type="text" name="from_address" required placeholder="From address" value="<?php if(isset($_POST["from_address"])) echo $from_address; ?>" size="30"> </td></tr> <tr><td><label>Subject</label><span style="color:#A60000">*</span></td> <td><input type="text" name="subject" required placeholder="Subject" value="<?php if(isset($_POST["subject"])) echo $subject; ?>" size="30"> </td></tr> <tr><td><label>Reply To</label><span style="color:#A60000">*</span></td> <td><input type="text" name="reply_to" required placeholder="Reply address" value="<?php if(isset($_POST["reply_to"])) echo $reply_to; ?>" size="30"> </td></tr> <tr><td><input type="submit" value="create report" style="background:#8AC007;color:#080808;padding:6px;" name="create_es_report"></td></tr> </table> </form> <?php //IF THERE ARE ERRORS, THEY WOULD BE DISPLAY HERE if (empty($errors) === false) { echo '<div>' . implode('</p><p>', $errors) . '</div>'; } } public function create_rp_report() { if (isset($_POST['create_rp_report'])) { $report_name = htmlentities($_POST['report_name']); $to_address = htmlentities($_POST['to_address']); $subject = htmlentities($_POST['subject']); $reply_to = htmlentities($_POST['reply_to']); if (empty($_POST['report_name']) || empty($_POST['to_address']) || empty($_POST['subject']) || empty($_POST['reply_to'])) { $errors[] = '<span class="error">All fields are required.</span>'; } else { if (isset($_POST['report_name']) && empty($_POST['report_name'])) { $errors[] = '<span class="error">Report Name is required</span>'; } else if (!ctype_alnum($_POST['report_name'])) { $errors[] = '<span class="error">Report Name: Whitespace is not allowed, only alphabets and numbers are required</span>'; } if (isset($_POST['to_address']) && empty($_POST['to_address'])) { $errors[] = '<span class="error">to address is required</span>'; } else if (filter_var($_POST['to_address'], FILTER_VALIDATE_EMAIL) === false) { $errors[] = '<span class="error">Please enter a valid to address</span>'; } if (isset($_POST['subject']) && empty($_POST['subject'])) { $errors[] = '<span class="error">Subject is required</span>'; } else if (!ctype_alnum($_POST['subject'])) { $errors[] = '<span class="error">Subject: Whitespace is not allowed, only alphabets and numbers are required</span>'; } if (isset($_POST['reply_to']) && empty($_POST['reply_to'])) { $errors[] = '<span class="error">Reply To is required</span>'; } else if (filter_var($_POST['reply_to'], FILTER_VALIDATE_EMAIL) === false) { $errors[] = '<span class="error">Please enter a valid Reply-To address</span>'; } } if (empty($errors) === true) { $query = $this->db->prepare("INSERT INTO report(report_name, to_address, subject, reply_to) VALUES (?, ?, ?, ?) "); $query->bindValue(1, $report_name); $query->bindValue(2, $to_address); $query->bindValue(3, $subject); $query->bindValue(4, $reply_to); try { $query->execute(); } catch(PDOException $e) { die($e->getMessage()); } header('Location:home.php?success'); exit(); } } if (isset($_GET['success']) && empty($_GET['success'])) { header('Location:home.php'); echo '<span class="error">Report is succesfully created</span>'; } ?> <form action="" method="POST" accept-charset="UTF-8"> <div style="font-weight:bold;padding:17px 80px;text-decoration:underline;">Section A</div> <table class="create_report"> <tr><td><label>Report Name</label><span style="color:#A60000">*</span></td> <td><input type="text" name="report_name" required placeholder="Name of the report" value="<?php if(isset($_POST["report_name"])) echo $report_name; ?>" size="30" maxlength="30"> </td></tr> <tr><td><label>to</label><span style="color:#A60000">*</span></td> <td><input type="text" name="to_address" required placeholder="to address" value="<?php if(isset($_POST["to_address"])) echo $to_address; ?>" size="30"> </td></tr> <tr><td><label>Subject</label><span style="color:#A60000">*</span></td> <td><input type="text" name="subject" required placeholder="Subject" value="<?php if(isset($_POST["subject"])) echo $subject; ?>" size="30"> </td></tr> <tr><td><label>Reply To</label><span style="color:#A60000">*</span></td> <td><input type="text" name="reply_to" required placeholder="Reply address" value="<?php if(isset($_POST["reply_to"])) echo $reply_to; ?>" size="30"> </td></tr> <tr><td><input type="submit" value="create report" style="background:#8AC007;color:#080808;padding:6px;" name="create_rp_report"></td></tr> </table> </form> <?php //IF THERE ARE ERRORS, THEY WOULD BE DISPLAY HERE if (empty($errors) === false) { echo '<div>' . implode('</p><p>', $errors) . '</div>'; } } }//Report CLASS ENDS

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• How do I use C# and ADO.NET to query an Oracle table with a spatial column of type SDO_GEOMETRY?

  - by John Donahue

  My development machine is running Windows 7 Enterprise, 64-bit version. I am using Visual Studio 2010 Release Candidate. I am connecting to an Oracle 11g Enterprise server version 11.1.0.7.0. I had a difficult time locating Oracle client software that is made for 64-bit Windows systems and eventually landed here to download what I assume is the proper client connectivity software. I added a reference to "Oracle.DataAccess" which is version 2.111.6.0 (Runtime Version is v2.0.50727). I am targeting .NET CLR version 4.0 since all properties of my VS Solution are defaults and this is 2010 RC. I was then able to write a console application in C# that established connectivity, executed a SELECT statement, and properly returned data when the table in question does NOT contain a spatial column. My problem is that this no longer works when the table I query has a column of type SDO_GEOMETRY in it. Below is the simple console application I am trying to run that reproduces the problem. When the code gets to the line with the "ExecuteReader" command, an exception is raised and the message is "Unsupported column datatype". using System; using System.Data; using Oracle.DataAccess.Client; namespace ConsoleTestOracle { class Program { static void Main(string[] args) { string oradb = string.Format("Data Source={0};User Id={1};Password={2};", "hostname/servicename", "login", "password"); try { using (OracleConnection conn = new OracleConnection(oradb)) { conn.Open(); OracleCommand cmd = new OracleCommand(); cmd.Connection = conn; cmd.CommandText = "select * from SDO_8307_2D_POINTS"; cmd.CommandType = CommandType.Text; OracleDataReader dr = cmd.ExecuteReader(); } } catch (Exception e) { string error = e.Message; } } } } The fact that this code works when used against a table that does not contain a spatial column of type SDO_GEOMETRY makes me think I have my windows 7 machine properly configured so I am surprised that I get this exception when the table contains different kinds of columns. I don't know if there is some configuration on my machine or the Oracle machine that needs to be done, or if the Oracle client software I have installed is wrong, or old and needs to be updated. Here is the SQL I used to create the table, populate it with some rows containing points in the spatial column, etc. if you want to try to reproduce this exactly. SQL Create Commands: create table SDO_8307_2D_Points (ObjectID number(38) not null unique, TestID number, shape SDO_GEOMETRY); Insert into SDO_8307_2D_Points values (1, 1, SDO_GEOMETRY(2001, 8307, null, SDO_ELEM_INFO_ARRAY(1, 1, 1), SDO_ORDINATE_ARRAY(10.0, 10.0))); Insert into SDO_8307_2D_Points values (2, 2, SDO_GEOMETRY(2001, 8307, null, SDO_ELEM_INFO_ARRAY(1, 1, 1), SDO_ORDINATE_ARRAY(10.0, 20.0))); insert into user_sdo_geom_metadata values ('SDO_8307_2D_Points', 'SHAPE', SDO_DIM_ARRAY(SDO_DIM_ELEMENT('Lat', -180, 180, 0.05), SDO_DIM_ELEMENT('Long', -90, 90, 0.05)), 8307); create index SDO_8307_2D_Point_indx on SDO_8307_2D_Points(shape) indextype is mdsys.spatial_index PARAMETERS ('sdo_indx_dims=2' ); Any advice or insights would be greatly appreciated. Thank you.

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• Why is my PHP query executing twice on page load?

  - by user1826238

  I am newish to PHP and I seem to be having an issue with an insert statement that executes twice when I open this page to view a document. In the database the 2nd insert is 1 second later. It happens in google chrome only and on this page only. IE has no issue, I dont have firefox to check. view_document.php <?php require_once($_SERVER['DOCUMENT_ROOT'] . '/../includes/core.php'); require_once($_SERVER['DOCUMENT_ROOT'] . '/../includes/connect.php'); $webusername = $_SESSION['webname']; if (isset($_GET['document'])) { $ainumber = (int) $_GET['document']; if (!ctype_digit($_GET['document']) || !preg_match('~^[0-9]+$~',$_GET['document']) || !is_numeric($_GET['document'])) { $_SESSION = array(); session_destroy(); header('Location: login.php'); } else { $stmt = $connect->prepare("SELECT s_filename, s_reference FROM dmsmain WHERE s_ainumber = ?") or die(mysqli_error()); $stmt->bind_param('s', $ainumber); $stmt->execute(); $stmt->bind_result($filename, $reference); $stmt->fetch(); $stmt->close(); $file = $_SERVER['DOCUMENT_ROOT'] . '/../dms/files/'.$filename.'.pdf'; if (file_exists($file)) { header('Content-Type: application/pdf'); header('Content-Disposition: inline; filename='.basename($file)); header('Content-Transfer-Encoding: binary'); header('Content-Length: ' . filesize($file)); header('Accept-Ranges: bytes'); readfile($file); $stmt = $connect->prepare("INSERT INTO dmslog (s_reference, s_userid, s_lastactivity, s_actiontype) VALUES (?, ?, ?, ?)") or die(mysqli_error()); date_default_timezone_set('Africa/Johannesburg'); $date = date('Y-m-d H:i:s'); $actiontype = 'DL'; $stmt->bind_param('ssss', $reference, $webusername, $date, $actiontype); $stmt->execute(); $stmt->close(); } else { $missing = "<b>File not found</b>"; } } } ?> My HTTP access records I assume [15/Nov/2012:10:14:32 +0200] "POST /dms/search.php HTTP/1.1" 200 5783 "http://www.denso.co.za/dms/search.php" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11" [15/Nov/2012:10:14:33 +0200] "GET /favicon.ico HTTP/1.1" 404 - "-" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11" [15/Nov/2012:10:14:34 +0200] "GET /dms/view_document.php?document=8 HTTP/1.1" 200 2965 "http://www.denso.co.za/dms/search.php" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11" [15/Nov/2012:10:14:35 +0200] "GET /favicon.ico HTTP/1.1" 404 - "-" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11" I have checked my <img src=''> links and I dont see a problem with them. The records indictate there is a favicon.ico request so I created a blank favicon and placed it in my public_html folder and linked it in the page like so <link href="../favicon.ico" rel="shortcut icon" type="image/x-icon" /> Unfortunately that did not work as the statement still executes twice. I am unsure if it is a favicon issue as my upload page uses an insert query and it executes once. If someone could please tell me where I am going wrong or point me in the right direction I would be very grateful

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• How to query on table returned by Stored procedure within a procedure.

  - by Shantanu Gupta

  I have a stored procedure that is performing some ddl dml operations. It retrieves a data after processing data from CTE and cross apply and other such complex things. Now this returns me a 4 tables which gets binded to various sources at frontend. Now I want to use one of the table to further processing so as to get more usefull information from it. eg. This table would be containing approx 2000 records at most of which i want to get records that belongs to lodging only. PK_CATEGORY_ID DESCRIPTION FK_CATEGORY_ID IMMEDIATE_PARENT Department_ID Department_Name DESCRIPTION_HIERARCHY DEPTH IS_ACTIVE ID_PATH DESC_PATH -------------------- -------------------------------------------------- -------------------- -------------------------------------------------- -------------------- -------------------------------------------------- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ----------- ----------- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 1 Food NULL NULL 1 Food (Food) Food 0 1 0 Food 5 Chinese 1 Food 1 Food (Food) ----Chinese 1 1 1 Food->Chinese 14 X 5 Chinese 1 Food (Food) --------X 2 1 1->5 Food->Chinese->X 15 Y 5 Chinese 1 Food (Food) --------Y 2 1 1->5 Food->Chinese->Y 65 asdasd 5 Chinese 1 Food (Food) --------asdasd 2 1 1->5 Food->Chinese->asdasd 66 asdas 5 Chinese 1 Food (Food) --------asdas 2 1 1->5 Food->Chinese->asdas 8 Italian 1 Food 1 Food (Food) ----Italian 1 1 1 Food->Italian 48 hfghfgh 1 Food 1 Food (Food) ----hfghfgh 1 1 1 Food->hfghfgh 55 Asd 1 Food 1 Food (Food) ----Asd 1 1 1 Food->Asd 2 Lodging NULL NULL 2 Lodging (Lodging) Lodging 0 1 0 Lodging 3 Room 2 Lodging 2 Lodging (Lodging) ----Room 1 1 2 Lodging->Room 4 Floor 3 Room 2 Lodging (Lodging) --------Floor 2 1 2->3 Lodging->Room->Floor 9 First 4 Floor 2 Lodging (Lodging) ------------First 3 1 2->3->4 Lodging->Room->Floor->First 10 Second 4 Floor 2 Lodging (Lodging) ------------Second 3 1 2->3->4 Lodging->Room->Floor->Second 11 Third 4 Floor 2 Lodging (Lodging) ------------Third 3 1 2->3->4 Lodging->Room->Floor->Third 29 Fourth 4 Floor 2 Lodging (Lodging) ------------Fourth 3 1 2->3->4 Lodging->Room->Floor->Fourth 12 Air Conditioned 3 Room 2 Lodging (Lodging) --------Air Conditioned 2 1 2->3 Lodging->Room->Air Conditioned 20 With Balcony 12 Air Conditioned 2 Lodging (Lodging) ------------With Balcony 3 1 2->3->12 Lodging->Room->Air Conditioned->With Balcony 24 Mountain View 20 With Balcony 2 Lodging (Lodging) ----------------Mountain View 4 1 2->3->12->20 Lodging->Room->Air Conditioned->With Balcony->Mountain View 25 Ocean View 20 With Balcony 2 Lodging (Lodging) ----------------Ocean View 4 1 2->3->12->20 Lodging->Room->Air Conditioned->With Balcony->Ocean View 26 Garden View 20 With Balcony 2 Lodging (Lodging) ----------------Garden View 4 1 2->3->12->20 Lodging->Room->Air Conditioned->With Balcony->Garden View 52 Smoking 20 With Balcony 2 Lodging (Lodging) ----------------Smoking 4 1 2->3->12->20 Lodging->Room->Air Conditioned->With Balcony->Smoking 21 Without Balcony 12 Air Conditioned 2 Lodging (Lodging) ------------Without Balcony 3 1 2->3->12 Lodging->Room->Air Conditioned->Without Balcony 13 Non Air Conditioned 3 Room 2 Lodging (Lodging) --------Non Air Conditioned 2 1 2->3 Lodging->Room->Non Air Conditioned 22 With Balcony 13 Non Air Conditioned 2 Lodging (Lodging) ------------With Balcony 3 1 2->3->13 Lodging->Room->Non Air Conditioned->With Balcony 71 EA 3 Room 2 Lodging (Lodging) --------EA 2 1 2->3 Lodging->Room->EA 50 Casabellas 2 Lodging 2 Lodging (Lodging) ----Casabellas 1 1 2 Lodging->Casabellas 51 North Beach 50 Casabellas 2 Lodging (Lodging) --------North Beach 2 1 2->50 Lodging->Casabellas->North Beach 40 Fooding NULL NULL 40 Fooding (Fooding) Fooding 0 1 0 Fooding 41 Pizza 40 Fooding 40 Fooding (Fooding) ----Pizza 1 1 40 Fooding->Pizza 45 Onion 41 Pizza 40 Fooding (Fooding) --------Onion 2 1 40->41 Fooding->Pizza->Onion 47 Extra Cheeze 41 Pizza 40 Fooding (Fooding) --------Extra Cheeze 2 1 40->41 Fooding->Pizza->Extra Cheeze 77 Burger 40 Fooding 40 Fooding (Fooding) ----Burger 1 1 40 Fooding->Burger This result is being obtained to me using some stored procedure which contains some DML operations as well. i want something like this select description from exec spName where fk_category_id=5 Remember that this spName is returning me 4 tables of which i want to perform some query on one of the table whose index will be known to me. I dont have to send it to UI before querying further. I am using Sql Server 2008 but would like a compatible solution for 2005 also.

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• Mysql - Help me alter this search query involving multiple joins and conditions to get the desired r

  - by sandeepan-nath

  About the system - We are following tags based search. Tutors create packs - tag relations for tutors stored in tutors_tag_relations and those for packs stored in learning_packs_tag_relations. All tags are stored in tags table. The system has 6 tables - tutors, Users (linked to tutor_details), learning_packs, learning_packs_tag_relations, tutors_tag_relations and tags Please run the following fresh queries to setup the system :- CREATE TABLE IF NOT EXISTS learning_packs_tag_relations ( id_tag int(10) unsigned NOT NULL DEFAULT '0', id_tutor int(10) DEFAULT NULL, id_lp int(10) unsigned DEFAULT NULL, KEY Learning_Packs_Tag_Relations_FKIndex1 (id_tag), KEY id_lp (id_lp), KEY id_tag (id_tag) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; CREATE TABLE IF NOT EXISTS learning_packs ( id_lp int(10) unsigned NOT NULL AUTO_INCREMENT, id_status int(10) unsigned NOT NULL DEFAULT '2', id_author int(10) unsigned NOT NULL DEFAULT '0', name varchar(255) NOT NULL DEFAULT '', PRIMARY KEY (id_lp) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=21 ; CREATE TABLE IF NOT EXISTS tutors_tag_relations ( id_tag int(10) unsigned NOT NULL DEFAULT '0', id_tutor int(10) DEFAULT NULL, KEY Tutors_Tag_Relations (id_tag), KEY id_tutor (id_tutor), KEY id_tag (id_tag) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; CREATE TABLE IF NOT EXISTS users ( id_user int(10) unsigned NOT NULL AUTO_INCREMENT, name varchar(100) NOT NULL DEFAULT '', surname varchar(155) NOT NULL DEFAULT '', PRIMARY KEY (id_user) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=52 ; CREATE TABLE IF NOT EXISTS tutor_details ( id_tutor int(10) NOT NULL AUTO_INCREMENT, id_user int(10) NOT NULL, PRIMARY KEY (id_tutor) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=60 ; CREATE TABLE IF NOT EXISTS tags ( id_tag int(10) unsigned NOT NULL AUTO_INCREMENT, tag varchar(255) DEFAULT NULL, PRIMARY KEY (id_tag), UNIQUE KEY tag (tag) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ; ALTER TABLE learning_packs_tag_relations ADD CONSTRAINT Learning_Packs_Tag_Relations_ibfk_1 FOREIGN KEY (id_tag) REFERENCES tags (id_tag) ON DELETE NO ACTION ON UPDATE NO ACTION; ALTER TABLE learning_packs ADD CONSTRAINT Learning_Packs_ibfk_2 FOREIGN KEY (id_author) REFERENCES users (id_user) ON DELETE NO ACTION ON UPDATE NO ACTION; ALTER TABLE tutors_tag_relations ADD CONSTRAINT Tutors_Tag_Relations_ibfk_1 FOREIGN KEY (id_tag) REFERENCES tags (id_tag) ON DELETE NO ACTION ON UPDATE NO ACTION; INSERT INTO test.users ( id_user , name , surname ) VALUES ( NULL , 'Vivian', 'Richards' ), ( NULL , 'Sachin', 'Tendulkar' ); INSERT INTO test.users ( id_user , name , surname ) VALUES ( NULL , 'Don', 'Bradman' ); INSERT INTO test.tutor_details ( id_tutor , id_user ) VALUES ( NULL , '52' ), ( NULL , '53' ); INSERT INTO test.tutor_details ( id_tutor , id_user ) VALUES ( NULL , '54' ); INSERT INTO test.tags ( id_tag , tag ) VALUES ( 1 , 'Vivian' ), ( 2 , 'Richards' ); INSERT INTO test.tags (id_tag, tag) VALUES (3, 'Sachin'), (4, 'Tendulkar'); INSERT INTO test.tags (id_tag, tag) VALUES (5, 'Don'), (6, 'Bradman'); INSERT INTO test.learning_packs (id_lp, id_status, id_author, name) VALUES ('1', '1', '52', 'Cricket 1'), ('2', '2', '52', 'Cricket 2'); INSERT INTO test.tags (id_tag, tag) VALUES ('7', 'Cricket'), ('8', '1'); INSERT INTO test.tags (id_tag, tag) VALUES ('9', '2'); INSERT INTO test.learning_packs_tag_relations (id_tag, id_tutor, id_lp) VALUES ('7', '52', '1'), ('8', '52', '1'); INSERT INTO test.learning_packs_tag_relations (id_tag, id_tutor, id_lp) VALUES ('7', '52', '2'), ('9', '52', '2'); =================================================================================== Requirement Now I want to search learning_packs, with the same AND logic. Help me modify the following query so that searching pack name or tutor's name, surname results all active packs (either directly those packs or packs created by those tutors). ================================================================================== select lp.* from Learning_Packs AS lp LEFT JOIN Learning_Packs_Tag_Relations AS lptagrels ON lp.id_lp = lptagrels.id_lp LEFT JOIN Tutors_Tag_Relations as ttagrels ON lp.id_author = ttagrels.id_tutor LEFT JOIN Tutor_Details AS td ON ttagrels.id_tutor = td.id_tutor LEFT JOIN Users as u on td.id_user = u.id_user JOIN Tags as t on (t.id_tag = lptagrels.id_tag) or (t.id_tag = ttagrels.id_tag) where lp.id_status = 1 AND ( t.tag LIKE "%Vivian%" OR t.tag LIKE "%Richards%" ) group by lp.id_lp HAVING count(lp.id_lp) 1 limit 0,20 As you can see, searching "Cricket 1" returns that pack but searching Vivian Richards does not return the same pack. Please help

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• Issue in Creating an Insert Query See Description Below...

  - by Parth

  I am creating a Insert Query using PHP.. By fetching the data from a Audit table and iterating the values of it in loops.. table from which I am fetching the value has the snapshot below: The Code I am using to create is given below: mysql_select_db('information_schema'); $select = mysql_query("SELECT TABLE_NAME FROM TABLES WHERE TABLE_SCHEMA = 'pranav_test'"); $selectclumn = mysql_query("SELECT * FROM COLUMNS WHERE TABLE_SCHEMA = 'pranav_test'"); mysql_select_db('pranav_test'); $seletaudit = mysql_query("SELECT * FROM jos_audittrail WHERE live = 0"); $tables = array(); $i = 0; while($row = mysql_fetch_array($select)) { $tables[$i++] =$row['TABLE_NAME']; } while($row2 = mysql_fetch_array($seletaudit)) { $audit[] =$row2; } foreach($audit as $val) { if($val['operation'] == "INSERT") { if(in_array($val['table_name'],$tables)) { $insert = "INSERT INTO '".$val['table_name']."' ("; $selfld = mysql_query("SELECT field FROM jos_audittrail WHERE table_name = '".$val['table_name']."' AND operation = 'INSERT' AND trackid = '".$val['trackid']."'"); while($row3 = mysql_fetch_array($selfld)) { $values[] = $row3; } foreach($values as $field) { $insert .= "'".$field['field']."', "; } $insert .= "]"; $insert = str_replace(", ]",")",$insert); $insert .= " values ("; $selval = mysql_query("SELECT newvalue FROM jos_audittrail WHERE table_name = '".$val['table_name']."' AND operation = 'INSERT' AND trackid = '".$val['trackid']."' AND live = 0"); while($row4 = mysql_fetch_array($selval)) { $value[] = $row4; } /*echo "<pre>"; print_r($value);exit;*/ foreach($value as $data) { $insert .= "'".$data['newvalue']."', "; } $insert .= "["; $insert = str_replace(", [",")",$insert); } } } When I Echo the $insert out of the most outer for loop (for auditrail) The values get printed as many times as the records are found for the outer for loop..i.e 'orderby= show_noauth= show_title= link_titles= show_intro= show_section= link_section= show_category= link_category= show_author= show_create_date= show_modify_date= show_item_navigation= show_readmore= show_vote= show_icons= show_pdf_icon= show_print_icon= show_email_icon= show_hits= feed_summary= page_title= show_page_title=1 pageclass_sfx= menu_image=-1 secure=0 ', '0000-00-00 00:00:00', '13', '20', '1', '152', 'accmenu', 'IPL', 'ipl', 'index.php?option=com_content&view=archive', 'component' gets repeated , i.e. INSERT INTO 'jos_menu' ('params', 'checked_out_time', 'ordering', 'componentid', 'published', 'id', 'menutype', 'name', 'alias', 'link', 'type', 'params', 'checked_out_time', 'ordering', 'componentid', 'published', 'id', 'menutype', 'name', 'alias', 'link', 'type', 'params', 'checked_out_time', 'ordering', 'componentid', 'published', 'id', 'menutype', 'name', 'alias', 'link', 'type', 'params', 'checked_out_time', 'ordering', 'componentid', 'published', 'id', 'menutype', 'name', 'alias', 'link', 'type', 'params', 'checked_out_time', 'ordering', 'componentid', 'published', 'id', 'menutype', 'name', 'alias', 'link', 'type', 'params', 'checked_out_time', 'ordering', 'componentid', 'published', 'id', 'menutype', 'name', 'alias', 'link', 'type', 'params', 'checked_out_time', 'ordering', 'componentid', 'published', 'id', 'menutype', 'name', 'alias', 'link', 'type', 'params', 'checked_out_time', 'ordering', 'componentid', 'published', 'id', 'menutype', 'name', 'alias', 'link', 'type', 'params', 'checked_out_time', 'ordering', 'componentid', 'published', 'id', 'menutype', 'name', 'alias', 'link', 'type', 'params', 'checked_out_time', 'ordering', 'componentid', 'published', 'id', 'menutype', 'name', 'alias', 'link', 'type', 'params', 'checked_out_time', 'ordering', 'componentid', 'published', 'id', 'menutype', 'name', 'alias', 'link', 'type') values ('orderby= show_noauth= show_title= link_titles= show_intro= show_section= link_section= show_category= link_category= show_author= show_create_date= show_modify_date= show_item_navigation= show_readmore= show_vote= show_icons= show_pdf_icon= show_print_icon= show_email_icon= show_hits= feed_summary= page_title= show_page_title=1 pageclass_sfx= menu_image=-1 secure=0 ', '0000-00-00 00:00:00', '13', '20', '1', '152', 'accmenu', 'IPL', 'ipl', 'index.php?option=com_content&view=archive', 'component', 'orderby= show_noauth= show_title= link_titles= show_intro= show_section= link_section= show_category= link_category= show_author= show_create_date= show_modify_date= show_item_navigation= show_readmore= show_vote= show_icons= show_pdf_icon= show_print_icon= show_email_icon= show_hits= feed_summary= page_title= show_page_title=1 pageclass_sfx= menu_image=-1 secure=0 ', '0000-00-00 00:00:00', '13', '20', '1', '152', 'accmenu', 'IPL', 'ipl', 'index.php?option=com_content&view=archive', 'component', 'orderby= show_noauth= .. .. .. .. and so on What I want is I should get these Values for once, I know there is mistake using the outer Forloop, but I m not getting the idea of rectifying it.. Please help... please poke me for more clarification...

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• Can I retrieve objects from a complex query that limits results to fields from a single table?

  - by Sean Redmond

  I have a model whose rows I always want to sort based on the values in another associated model and I was thinking that the way to implement this would be to use set_dataset in the model. This is causing query results to be returned as hashes rather than objects, though, so none of the methods from the class can be used when iterating over the dataset. I basically have two classes class SortFields < Sequel::Model(:sort_fields) set_primary_key :objectid end class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid end Some backstory: the data is imported from a legacy system into mysql. The values in sort_fields are calculated from multiple other associated tables (some one-to-many, some many-to-many) according to some complicated rules. The likely solution will be to just add the values in sort_fields to items (I want to keep the imported data separate from the calculated data, but I don't have to). First, though, I just want to understand how far you can go with a dataset and still get objects rather than hashes. If I set the dataset to sort on a field in items like so class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid set_dataset(order(:sortnumber)) end then the expected clause is added to the generated SQL, e.g.: >> Items.limit(1).sql => "SELECT * FROM `items` ORDER BY `sortnumber` LIMIT 1" and queries still return objects: >> Items.limit(1).first.class => Items If I order it by the associated fields though... class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid set_dataset( eager_graph(:sort_fields). order(:sort1, :sort2, :sort3) ) end ...I get hashes ?> Items.limit(1).first.class => Hash My first thought was that this happens because all fields from sort_fields are included in the results and maybe if selected only the fields from items I would get Items objects again: class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid set_dataset( eager_graph(:sort_fields). select(:items.*). order(:sort1, :sort2, :sort3) ) end The generated SQL is what I would expect: >> Items.limit(1).sql => "SELECT `items`.* FROM `items` LEFT OUTER JOIN `sort_fields` ON (`sort_fields`.`objectid` = `items`.`objectid`) ORDER BY `sort1`, `sort2`, `sort3` LIMIT 1" It returns the same rows as the set_dataset(order(:sortnumber)) version but it still doesn't work: >> Items.limit(1).first.class => Hash Before I add the sort fields to the items table so that they can all live happily in the same model, is there a way to tell Sequel to return on object when it wants to return a hash?

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• Parallelism in .NET – Part 11, Divide and Conquer via Parallel.Invoke

  - by Reed

  Many algorithms are easily written to work via recursion.  For example, most data-oriented tasks where a tree of data must be processed are much more easily handled by starting at the root, and recursively “walking” the tree.  Some algorithms work this way on flat data structures, such as arrays, as well.  This is a form of divide and conquer: an algorithm design which is based around breaking up a set of work recursively, “dividing” the total work in each recursive step, and “conquering” the work when the remaining work is small enough to be solved easily. Recursive algorithms, especially ones based on a form of divide and conquer, are often a very good candidate for parallelization. This is apparent from a common sense standpoint.  Since we’re dividing up the total work in the algorithm, we have an obvious, built-in partitioning scheme.  Once partitioned, the data can be worked upon independently, so there is good, clean isolation of data. Implementing this type of algorithm is fairly simple.  The Parallel class in .NET 4 includes a method suited for this type of operation: Parallel.Invoke.  This method works by taking any number of delegates defined as an Action, and operating them all in parallel.  The method returns when every delegate has completed: Parallel.Invoke( () => { Console.WriteLine("Action 1 executing in thread {0}", Thread.CurrentThread.ManagedThreadId); }, () => { Console.WriteLine("Action 2 executing in thread {0}", Thread.CurrentThread.ManagedThreadId); }, () => { Console.WriteLine("Action 3 executing in thread {0}", Thread.CurrentThread.ManagedThreadId); } ); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Running this simple example demonstrates the ease of using this method.  For example, on my system, I get three separate thread IDs when running the above code.  By allowing any number of delegates to be executed directly, concurrently, the Parallel.Invoke method provides us an easy way to parallelize any algorithm based on divide and conquer.  We can divide our work in each step, and execute each task in parallel, recursively. For example, suppose we wanted to implement our own quicksort routine.  The quicksort algorithm can be designed based on divide and conquer.  In each iteration, we pick a pivot point, and use that to partition the total array.  We swap the elements around the pivot, then recursively sort the lists on each side of the pivot.  For example, let’s look at this simple, sequential implementation of quicksort: public static void QuickSort<T>(T[] array) where T : IComparable<T> { QuickSortInternal(array, 0, array.Length - 1); } private static void QuickSortInternal<T>(T[] array, int left, int right) where T : IComparable<T> { if (left >= right) { return; } SwapElements(array, left, (left + right) / 2); int last = left; for (int current = left + 1; current <= right; ++current) { if (array[current].CompareTo(array[left]) < 0) { ++last; SwapElements(array, last, current); } } SwapElements(array, left, last); QuickSortInternal(array, left, last - 1); QuickSortInternal(array, last + 1, right); } static void SwapElements<T>(T[] array, int i, int j) { T temp = array[i]; array[i] = array[j]; array[j] = temp; } Here, we implement the quicksort algorithm in a very common, divide and conquer approach.  Running this against the built-in Array.Sort routine shows that we get the exact same answers (although the framework’s sort routine is slightly faster).  On my system, for example, I can use framework’s sort to sort ten million random doubles in about 7.3s, and this implementation takes about 9.3s on average. Looking at this routine, though, there is a clear opportunity to parallelize.  At the end of QuickSortInternal, we recursively call into QuickSortInternal with each partition of the array after the pivot is chosen.  This can be rewritten to use Parallel.Invoke by simply changing it to: // Code above is unchanged... SwapElements(array, left, last); Parallel.Invoke( () => QuickSortInternal(array, left, last - 1), () => QuickSortInternal(array, last + 1, right) ); } This routine will now run in parallel.  When executing, we now see the CPU usage across all cores spike while it executes.  However, there is a significant problem here – by parallelizing this routine, we took it from an execution time of 9.3s to an execution time of approximately 14 seconds!  We’re using more resources as seen in the CPU usage, but the overall result is a dramatic slowdown in overall processing time. This occurs because parallelization adds overhead.  Each time we split this array, we spawn two new tasks to parallelize this algorithm!  This is far, far too many tasks for our cores to operate upon at a single time.  In effect, we’re “over-parallelizing” this routine.  This is a common problem when working with divide and conquer algorithms, and leads to an important observation: When parallelizing a recursive routine, take special care not to add more tasks than necessary to fully utilize your system. This can be done with a few different approaches, in this case.  Typically, the way to handle this is to stop parallelizing the routine at a certain point, and revert back to the serial approach.  Since the first few recursions will all still be parallelized, our “deeper” recursive tasks will be running in parallel, and can take full advantage of the machine.  This also dramatically reduces the overhead added by parallelizing, since we’re only adding overhead for the first few recursive calls.  There are two basic approaches we can take here.  The first approach would be to look at the total work size, and if it’s smaller than a specific threshold, revert to our serial implementation.  In this case, we could just check right-left, and if it’s under a threshold, call the methods directly instead of using Parallel.Invoke. The second approach is to track how “deep” in the “tree” we are currently at, and if we are below some number of levels, stop parallelizing.  This approach is a more general-purpose approach, since it works on routines which parse trees as well as routines working off of a single array, but may not work as well if a poor partitioning strategy is chosen or the tree is not balanced evenly. This can be written very easily.  If we pass a maxDepth parameter into our internal routine, we can restrict the amount of times we parallelize by changing the recursive call to: // Code above is unchanged... SwapElements(array, left, last); if (maxDepth < 1) { QuickSortInternal(array, left, last - 1, maxDepth); QuickSortInternal(array, last + 1, right, maxDepth); } else { --maxDepth; Parallel.Invoke( () => QuickSortInternal(array, left, last - 1, maxDepth), () => QuickSortInternal(array, last + 1, right, maxDepth)); } We no longer allow this to parallelize indefinitely – only to a specific depth, at which time we revert to a serial implementation.  By starting the routine with a maxDepth equal to Environment.ProcessorCount, we can restrict the total amount of parallel operations significantly, but still provide adequate work for each processing core. With this final change, my timings are much better.  On average, I get the following timings: Framework via Array.Sort: 7.3 seconds Serial Quicksort Implementation: 9.3 seconds Naive Parallel Implementation: 14 seconds Parallel Implementation Restricting Depth: 4.7 seconds Finally, we are now faster than the framework’s Array.Sort implementation.

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• Is recursion really bad?

  - by dotneteer

  After my previous post about the stack space, it appears that there is perception from the feedback that recursion is bad and we should avoid deep recursion. After writing a compiler, I know that the modern computer and compiler are complex enough and one cannot automatically assume that a hand crafted code would out-perform the compiler optimization. The only way is to do some prototype to find out. So why recursive code may not perform as well? Compilers place frames on a stack. In additional to arguments and local variables, compiles also need to place frame and program pointers on the frame, resulting in overheads. So why hand-crafted code may not performance as well? The stack used by a compiler is a simpler data structure and can grow and shrink cleanly. To replace recursion with out own stack, our stack is allocated in the heap that is far more complicated to manage. There could be overhead as well if the compiler needs to mark objects for garbage collection. Compiler also needs to worry about the memory fragmentation. Then there is additional complexity: CPUs have registers and multiple levels of cache. Register access is a few times faster than in-CPU cache access and is a few 10s times than on-board memory access. So it is up to the OS and compiler to maximize the use of register and in-CPU cache. For my particular problem, I did an experiment to rewrite my c# version of recursive code with a loop and stack approach. So here are the outcomes of the two approaches:   Recursive call Loop and Stack Lines of code for the algorithm 17 46 Speed Baseline 3% faster Readability Clean Far more complex So at the end, I was able to achieve 3% better performance with other drawbacks. My message is never assuming your sophisticated approach would automatically work out better than a simpler approach with a modern computer and compiler. Gage carefully before committing to a more complex approach.

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• What happens to C# 4 optional parameters when compiling against 3.5?

  - by Bertrand Le Roy

  Here’s a method declaration that uses optional parameters: public Path Copy( Path destination, bool overwrite = false, bool recursive = false) Something you may not know is that Visual Studio 2010 will let you compile this against .NET 3.5, with no error or warning. You may be wondering (as I was) how it does that. Well, it takes the easy and rather obvious way of not trying to be too smart and just ignores the optional parameters. So if you’re compiling against 3.5 from Visual Studio 2010, the above code is equivalent to: public Path Copy( Path destination, bool overwrite, bool recursive) The parameters are not optional (no such thing in C# 3), and no overload gets magically created for you. If you’re building a library that is going to have both 3.5 and 4.0 versions, and you want 3.5 users to have reasonable overloads of your methods, you’ll have to provide those yourself, which means that providing a version with optional parameters for the benefit of 4.0 users is not going to provide that much value, except for the ability to provide named parameters out of order. I guess that’s not so bad… Providing all of the following overloads will compile against both 3.5 and 4.0: public Path Copy(Path destination)public Path Copy(Path destination, bool overwrite)public Path Copy( Path destination, bool overwrite = false, bool recursive = false)

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• Is it just me or is this a baffling tech interview question

  - by Matthew Patrick Cashatt

  Background I was just asked in a tech interview to write an algorithm to traverse an "object" (notice the quotes) where A is equal to B and B is equal to C and A is equal to C. That's it. That is all the information I was given. I asked the interviewer what the goal was but apparently there wasn't one, just "traverse" the "object". I don't know about anyone else, but this seems like a silly question to me. I asked again, "am I searching for a value?". Nope. Just "traverse" it. Why would I ever want to endlessly loop through this "object"?? To melt my processor maybe?? The answer according to the interviewer was that I should have written a recursive function. OK, so why not simply ask me to write a recursive function? And who would write a recursive function that never ends? My question: Is this a valid question to the rest of you and, if so, can you provide a hint as to what I might be missing? Perhaps I am thinking too hard about solving real world problems. I have been successfully coding for a long time but this tech interview process makes me feel like I don't know anything. Final Answer: CLOWN TRAVERSAL!!! (See @Matt's answer below) Thanks! Matt

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• SQL Profiler: Read/Write units

  - by Ian Boyd

  i've picked a query out of SQL Server Profiler that says it took 1,497 reads: EventClass: SQL:BatchCompleted TextData: SELECT Transactions.... CPU: 406 Reads: 1497 Writes: 0 Duration: 406 So i've taken this query into Query Analyzer, so i may try to reduce the number of reads. But when i turn on SET STATISTICS IO ON to see the IO activity for the query, i get nowhere close to one thousand reads: Table Scan Count Logical Reads =================== ========== ============= FintracTransactions 4 20 LCDs 2 4 LCTs 2 4 FintracTransacti... 0 0 Users 1 2 MALs 0 0 Patrons 0 0 Shifts 1 2 Cages 1 1 Windows 1 3 Logins 1 3 Sessions 1 6 Transactions 1 7 Which if i do my math right, there is a total of 51 reads; not 1,497. So i assume Reads in SQL Profiler is an arbitrary metric. Does anyone know the conversion of SQL Server Profiler Reads to IO Reads? See also SQL Profiler CPU / duration unit Query Analyzer VS. Query Profiler Reads, Writes, and Duration Discrepencies

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• Filtering by entity key name in Google App Engine on Python

  - by Bemmu

  On Google App Engine to query the data store with Python, one can use GQL or Entity.all() and then filter it. So for example these are equivalent gql = "SELECT * FROM User WHERE age >= 18" db.GqlQuery(gql) and query = User.all() query.filter("age >=", 18) Now, it's also possible to query things by key name. I know that in GQL you do it like this gql = "SELECT * FROM User WHERE __key__ >= Key('User', 'abc')" db.GqlQuery(gql) But how would you now use filter to do the same? query = User.all() query.filter("__key__ >=", ?????)

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• Using Static methods or none static methods in Dao Class ?

  - by dankyy1

  Hi I generate Dao classes for some DB operations in this manner making methods of Dao class as static or none static is better? Using sample dao class below ,If more than one client got to use the AddSampleItem method in same time?how this may result? public class SampleDao { static DataAcessor dataAcessor public static void AddSampleItem(object[] params) { dataAcessor =new DataAcessor(); //generate query here string query="..." dataAcessor.ExecuteQery(query); dataAcessor.Close(); } public static void UpdateSampleItem(object[] params) { dataAcessor =new DataAcessor(); //generate query here string query="..." dataAcessor.ExecuteQery(query); dataAcessor.Close(); } }

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• PHP - static DB class vs DB singleton object

  - by Marco Demaio

  I don't want to create a discussion about singleton better than static or better than global, etc. I read dozens of questions about it on SO, but I couldn't come up with an answer to this SPECIFIC question, so I hope someone could now illuminate me buy answering this question with one (or more) real simple EXAMPLES, and not theoretical discussions. In my app I have the typical DB class needed to perform tasks on DB without having to write everywhere in code mysql_connect/mysql_select_db/mysql... (moreover in future I might decide to use another type of DB engine in place of mySQL so obviously I need a class of abstration). I could write the class either as a static class: class DB { private static $connection = FALSE; //connection to be opened //DB connection values private static $server = NULL; private static $usr = NULL; private static $psw = NULL; private static $name = NULL; public static function init($db_server, $db_usr, $db_psw, $db_name) { //simply stores connections values, withour opening connection } public static function query($query_string) { //performs query over alerady opened connection, if not open, it opens connection 1st } ... } or as a Singletonm class: class DBSingleton { private $inst = NULL; private $connection = FALSE; //connection to be opened //DB connection values private $server = NULL; private $usr = NULL; private $psw = NULL; private $name = NULL; public static function getInstance($db_server, $db_usr, $db_psw, $db_name) { //simply stores connections values, withour opening connection if($inst === NULL) $this->inst = new DBSingleton(); return $this->inst; } private __construct()... public function query($query_string) { //performs query over already opened connection, if connection is not open, it opens connection 1st } ... } Then after in my app if I wanto to query the DB i could do //Performing query using static DB object DB:init(HOST, USR, PSW, DB_NAME); DB::query("SELECT..."); //Performing query using DB singleton $temp = DBSingleton::getInstance(HOST, USR, PSW, DB_NAME); $temp->query("SELECT..."); My simple brain sees Singleton has got the only advantage to avoid declaring as 'static' each method of the class. I'm sure some of you could give me an EXAMPLE of real advantage of singleton in this specific case. Thanks in advance.

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