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• Modifying SQL Database on Shared Hosting

  - by apocalypse9

  I have a live database on a shared hosting server. I am making some major changes to my site's code and I would like to fix some stupid mistakes I made in initially designing the database. These changes involve altering the size of a large number of fields, and enforcing referential integrity between tables properly. I would like to make the changes on both my local test server and the remote server if possible. I should note that while I'm fairly comfortable with writing complex queries to handle data, I have very little experience modifying database structure without a graphical interface. I can access the remote database in the visual studio database explorer but I can not use that for anything other than data manipulation. I installed Sql Management Studio express last night and after 40+ crashes I gave up - I couldn't even patch the damn thing. The remote server is SQL 2005 / The MyLittleAdmin web interface is available. So my question is what is the best way to accomplish these changes. Is there a graphical interface I can use on the remote server? If not is there an easy way to copy the database to my local machine, fix it, and re upload? Finally if none of the above are viable does anyone have links to a decent info on fixing referential integrity via query? Sorry for the somewhat general question - I feel like I am making this far harder than it should be but after searching / trying all night i haven't gotten anywhere. Thanks in advance for the help. I really appreciate it. ...Also does anyone have a time machine I can borrow- I need to go kick my past self's ass for this.

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• error while reading Excel sheet

  - by Lalit

  Hi, I have code to read Excel from c3 language : DataTable dtChildrenData = new DataTable(); OdbcConnection oConn = null; try { if (File.Exists(strSheetPath)) { oConn = new OdbcConnection(); oConn.ConnectionString = @"DSN=Excel Files;DBQ=" + strSheetPath + @";DriverId=1046;FIL=excel 12.0;MaxBufferSize=2048;PageTimeout=5;"; OdbcCommand oComm = new OdbcCommand(); oComm.Connection = oConn; oComm.CommandText = "Select * From [Sheet1$]"; DataSet ds = new DataSet(); OdbcDataAdapter oAdapter = new OdbcDataAdapter(oComm); oConn.Open(); oAdapter.Fill(ds); dtChildrenData = ds.Tables[0]; } } finally { oConn.Close(); } return dtChildrenData; But getting this error when i deploy the web application on IIS. Wherere as it is running fine locally. ERROR [IM002] [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified How to solve this. Please let me know if any information required to answer this question (about configuration)

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• Can't diagnose my MySQL root user problem

  - by George Crawford

  Hi all, I have a problem with the MySQL root user in My MySQL setup, and I just can't for the life of me work out how to fix it. It seems that I have somehow messed up the root user, and my access to databases is now very erratic. For reference, I'm using MAMP on OS X to provide the MySQL server. I'm not sure how much that matters though - I'd guess that whatever I've done will require a command-line fix to solve it. I can start MySQL using MAMP as usual, and access databases using the 'standard' users I have created for my PHP apps. However, the root user, which I use in my MySQL GUI client, and also in phpMyAdmin, can only access the "information_schema" database, as well as two I have created manually, and presumably (and mistakenly) left permissions wide open for. My 15 or so other databases cannot be accessed my the root user. When I load up phpMyAdmin, the home screen says: "Create new database: No Privileges". I certainly did at some stage change my root user's password using the MAMP dialog. But I don't remember if I did anything else which might have caused this problem. I've tried changing the password again, and there seems to be no change in the issue. I've also tried resetting root password using the command line, including starting mysql manually with --skip-grant-tables then flushing privs, but again, nothing seems to fix the issue. I've come to the end of my ideas, and would very much appreciate some step-by-step advice and diagnosis from one of the experts here! Many thanks for your help.

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• How to track auto-generated id's in select-insert statement

  - by k rey

  I have two tables detail and head. The detail table will be written first. Later, the head table will be written. The head is a summary of the detail table. I would like to keep a reference from the detail to the head table. I have a solution but it is not elegant and requires duplicating the joins and filters that were used during summation. I am looking for a better solution. The below is an example of what I currently have. In this example, I have simplified the table structure. In the real world, the summation is very complex. -- Preparation create table #detail ( detail_id int identity(1,1) , code char(4) , amount money , head_id int null ); create table #head ( head_id int identity(1,1) , code char(4) , subtotal money ); insert into #detail ( code, amount ) values ( 'A', 5 ); insert into #detail ( code, amount ) values ( 'A', 5 ); insert into #detail ( code, amount ) values ( 'B', 2 ); insert into #detail ( code, amount ) values ( 'B', 2 ); -- I would like to somehow simplify the following two queries insert into #head ( code, subtotal ) select code, sum(amount) from #detail group by code update #detail set head_id = h.head_id from #detail d inner join #head h on d.code = h.code -- This is the desired end result select * from #detail Desired end result of detail table: detail_id code amount head_id 1 A 5.00 1 2 A 5.00 1 3 B 2.00 2 4 B 2.00 2

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• Foreign key relationships in Entity Framework

  - by Anders Svensson

  I'm trying to add an object created from Entity Data Model classes. I have a table called Users, which has turned into a User EDM class. And I also have a table Pages, which has become a Page EDM class. These tables have a foreign key relationship, so that each page is associated with many users. Now I want to be able to add a page, but I can't get how to do it. I get a nullreference exception on Users below. I'm still rather confused by all this, so I'm sure it's a simple error, but I just can't see how to do it. Also, by the way, the compiler requires that I set PageID in the object initializer, even though this field is set to be an automatic id in the table. Am I doing it right just setting it to 0, expecting it to be updated automatically in the table when saved, or how should I do that? Any help appreciated! The method in question: private Page GetPage(User currentUser) { string url = _request.ServerVariables["url"].ToLower(); var userPages = from p in _context.PageSet where p.Users.UserID == currentUser.UserID select p; var existingPage = userPages.FirstOrDefault(e => e.Url == url); //Could be combined with above, but hard to read? if (existingPage != null) return existingPage; Page page = new Page() { Count = 0, Url = _request.ServerVariables["url"].ToLower(), PageID = 0, //Only initial value, changed later? }; _context.AddToPageSet(page); page.Users.UserID = currentUser.UserID; //Here's the problem... return page; }

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• Binding value for NSTableView, but tooltip gets set as well

  - by Mark

  I've set up an NSTableView in Interface Builder to be populated from an NSArray. Each value of the array represents one row in the table. The value is bound correctly, but as a side effect, the table cell's tooltip is set to the string representation of the bound object. In my case, the NSArray contains NSDictiorany objects and the tooltip looks like it could be the [... description] output of that dictionary. Very ugly... I don't want the tooltip to be set at all. I have other tables that have plain NSString values bound to them and they don't have a tooltip set automatically. Is there some Interface Builder magic going on? I tried to start with a blank project - same problem. I should add that the table cell is a custom implementation of NSTextFieldCell that uses an NSButtonCell instance to draw an image and a label into the table. The values are retrieved from the dictionary bound as value. Why is the tooltip set when I only bind the "value" attribute? Thanks in advance!

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• How SQLite on Android handles long strings?

  - by Levara

  I'm wondering how Android's implementation of SQLite handles long Strings. Reading from online documentation on sqlite, it said that strings in sqlite are limited to 1 million characters. My strings are definitely smaller. I'm creating a simple RSS application, and after parsing a html document, and extracting text, I'm having problem saving it to a database. I have 2 tables in database, feeds and articles. RSS feeds are correctly saved and retrieved from feeds table, but when saving to the articles table, logcat is saying that it cannot save extracted text to it's column. I don't know if other columns are making problems too, no mention of them in logcat. I'm wondering, since text is from an article on web, are signs like (",',;) creating problems? Is Android automaticaly escaping them, or I have to do that. I'm using a technique for inserting similar to one in notepad tutorial: public long insertArticle(long feedid, String title, String link, String description, String h1,tring h2, String h3, String p, String image, long date) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_FEEDID, feedid); initialValues.put(KEY_TITLE, title); initialValues.put(KEY_LINK, link); initialValues.put(KEY_DESCRIPTION, description ); initialValues.put(KEY_H1, h1 ); initialValues.put(KEY_H2, h2); initialValues.put(KEY_H3, h3); initialValues.put(KEY_P, p); initialValues.put(KEY_IMAGE, image); initialValues.put(KEY_DATE, date); return mDb.insert(DATABASE_TABLE_ARTICLES,null, initialValues); } Column P is for extracted text, h1, h2 and h3 are for headers from a page. Logcat reports only column p to be the problem. The table is created with following statement: private static final String DATABASE_CREATE_ARTICLES = "create table articles( _id integer primary key autoincrement, feedid integer, title text, link text not null, description text," + "h1 text, h2 text, h3 text, p text, image text, date integer);";

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• A typical mysql query( how to use subquery column into main query)

  - by I Like PHP

  I HAVE TWO TABLES shown below table_joining id join_id(PK) transfer_id(FK) unit_id transfer_date joining_date 1 j_1 t_1 u_1 2010-06-05 2010-03-05 2 j_2 t_2 u_3 2010-05-10 2010-03-10 3 j_3 t_3 u_6 2010-04-10 2010-01-01 4 j_5 NULL u_3 NULL 2010-06-05 5 j_6 NULL u_4 NULL 2010-05-05 table_transfer id transfer_id(PK) pastUnitId futureUnitId effective_transfer_date 1 t_1 u_3 u_1 2010-06-05 2 t_2 u_6 u_1 2010-05-10 3 t_3 u_5 u_3 2010-04-10 now i want to know total employee detalis( using join_id) which are currently working on unit u_3 . means i want only join_id j_1 (has transfered but effective_transfer_date is future date, right now in u_3) j_2 ( tansfered and right now in `u_3` bcoz effective_transfer_date has been passed) j_6 ( right now in `u_3` and never transfered) what i need to take care of below steps( as far as i know ) <1> first need to check from table_joining whether transfer_id is NULL or not <2> if transfer_id= is NULL then see unit_id=u_3 where joining_date <=CURDATE() ( means that person already joined u_3) <3> if transfer_id is NOT NULL then go to table_transfer using transfer_id (foreign key reference) <4> now see the effective_transfer_date regrading that transfer_id whether effective_transfer_date<=CURDATE() <5> if transfer date has been passed(means transfer has been done) then return futureUnitID otherwise return pastUnitID i used two separate query but don't know how to join those query?? for step <1 ans <2 SELECT unit_id FROM table_joining WHERE joining_date<=CURDATE() AND transfer_id IS NULL AND unit_id='u_3' for step<5 SELECT IF(effective_transfer_date <= CURDATE(),futureUnitId,pastUnitId) AS currentUnitID FROM table_transfer // here how do we select only those rows which have currentUnitID='u_3' ?? please guide me the process?? i m just confused with JOINS. i think using LEFT JOIN can return the data i need, or if we use subquery value to main query? but i m not getting how to implement ...please help me. Thanks for helping me alwayz

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• MySQL " identify storage engine statement"

  - by sammysmall

  This IS NOT a Homework question! While building my current student database project I realized that I may want to identify comprehensive information about a database design in the future. More-so if I am fortunate enough to get a job in this field and were handed a database project how could I break down certain elements for identification... In all of my previous designs I have been using MySQL Community Server (GPL) 5.1.42, I thought (duh) that I was using the MyISAM based on most of my text-book instruction and MySQL 5.0 Reference Manual :: 13 Storage Engines :: 13.1 The MyISAM Storage Engine I determined that this was in fact incorrect for this version and the use of "SHOW ENGINES" at the console... No problem, figured out why they have "versions" the need to pay attention to what version is being used, and the need for a means to determine what I am about to mess up "if" I do not pay attention to detail... Q1. Specifically what statement will identify the version used by someone elses initial database creation? (since I created my own databases I know what version I used) Q2. Specifically what statement will identify the storage engine that the developer used when creating the database. (I specified a particular database in my collection then tried SHOW Engine, did not work, then tried to just get the metadata from one table in that database: mysql SELECT duck_cust, table_type, engine - FROM INFORMATION_SCHEMA.tables - WHERE table_schema = 'tp' - ORDER BY table_type ASC, table_name DESC; as this was not really what I wanted (and did not work) I am looking for some direction from the pros... Q3. (If you really have the inclination to continue helping) If I were to access a database from an earlier/later "version" are there backward/forward compatibility issues for maintaining/updating data between versions? Please and Thank you in advance for your time and efforts! sammysmall

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• NSNotification vs. Delegate Protocols?

  - by jr

  I have an iPhone application which basically is getting information from an API (in XML, but maybe JSON eventually). The result objects are typically displayed in view controllers (tables mainly). Here is the architecture right now. I have NSOperation classes which fetch the different objects from the remote server. Each of these NSOperation classes, will take a custom delegate method which will fire back the resulting objects as they are parsed, and then finally a method when no more results are available. So, the protocol for the delegates will be something like: (void) ObjectTypeResult:(ObjectType *)result; (void) ObjectTypeNoMoreResults; I think the solution works well, but I do end up with a bunch of delegate protocols around and then my view controllers have to implement all these delegate methods. I don't think its that bad, but I'm always on the lookout for a better design. So, I'm thinking about using NSNotifications to remove the use of the delegates. I could include the object in the userInfo part of the notification and just post objects as received, and then a final event when no more are available. Then I could just have one method in each view controller to receive all the data, even when using multiple objects in one controller.† So, can someone share with me some pros/cons of each approach. Should I consider refactoring my code to use Events rather then the delegates? Is one better then the other in certain situations? In my scenario I'm really not looking to receive notifications in multiple places, so maybe the protocol based delegates are the way to go. Thanks!

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• SQL connection to database repeating

  - by user175084

  ok now i am using the SQL database to get the values from different tables... so i make the connection and get the values like this: DataTable dt = new DataTable(); SqlConnection connection = new SqlConnection(); connection.ConnectionString = ConfigurationManager.ConnectionStrings["XYZConnectionString"].ConnectionString; connection.Open(); SqlCommand sqlCmd = new SqlCommand("SELECT * FROM Machines", connection); SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCmd); sqlCmd.Parameters.AddWithValue("@node", node); sqlDa.Fill(dt); connection.Close(); so this is one query on the page and i am calling many other queries on the page. So do i need to open and close the connection everytime...??? also if not this portion is common in all: DataTable dt = new DataTable(); SqlConnection connection = new SqlConnection(); connection.ConnectionString = ConfigurationManager.ConnectionStrings["XYZConnectionString"].ConnectionString; connection.Open(); can i like put it in one function and call it instead.. the code would look cleaner... i tried doing that but i get errors like: Connection does not exist in the current context. any suggestions??? thanks

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• Big-O for calculating all routes from GPS data

  - by HH

  A non-critical GPS module use lists because it needs to be modifiable, new routes added, new distances calculated, continuos comparisons. Well so I thought but my team member wrote something I am very hard to get into. His pseudo code int k =0; a[][] <- create mapModuleNearbyDotList -array //CPU O(n) for(j = 1 to n) // O(nlog(m)) for(i =1 to n) for(k = 1 to n) if(dot is nearby) adj[i][j]=min(adj[i][j], adj[i][k] + adj[k][j]); His ideas transformations of lists to tables His worst case time complexity is O(n^3), where n is number of elements in his so-called table. Exception to the last point with Finite structure: O(mlog(n)) where n is number of vertices and m is the amount of neighbour vertices. Questions about his ideas why to waste resources to transform constantly-modified lists to table? Fast? only point where I to some extent agree but cannot understand the same upper limits n for each for-loops -- perhaps he supposed it circular why does the code take O(mlog(n)) to proceed in time as finite structure? The term finite may be wrong, explicit?

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• Why does grails use hsqldb when I ask for mysql?

  - by John

  I'm following the racetrack example from Jason Rudolph's book at InfoQ, using grails-1.2.1. I got up to the part where I was to switch from hsqldb to mysql. I think I've deleted every reference to hsqldb in the DataSource.groovy file, but I get an exception and the stack trace shows it's still using hsqldb. DataSource.groovy dataSource { boolean pooled = true String driverClassName = "com.mysql.jdbc.Driver" String url = "jdbc:mysql://localhost/dfpc2" String dbCreate = "create" String username = "dfpc2" String password = "dfpc2" dialect = org.hibernate.dialect.MySQL5InnoDBDialect } hibernate { cache.use_second_level_cache=true cache.use_query_cache=true cache.provider_class='net.sf.ehcache.hibernate.EhCacheProvider' } // environment specific settings environments { development { } test { } production { } } When I grails run-app it all starts up with no errors. I can navigate to the home page. But when I click on one of the links, I get a stack trace: java.sql.SQLException: Table not found in statement [select this_.id as id0_0_, this_.version as version0_0_, this_.name as name0_0_, this_.variant as variant0_0_ from domainObject this_ limit ?] at org.hsqldb.jdbc.Util.throwError(Unknown Source) at org.hsqldb.jdbc.jdbcPreparedStatement.<init>(Unknown Source) at org.hsqldb.jdbc.jdbcConnection.prepareStatement(Unknown Source) at dfpc2.domainObjectController$_closure2.doCall(script1269434425504953491149.groovy:13) at dfpc2.domainObjectController$_closure2.doCall(script1269434425504953491149.groovy) at java.lang.Thread.run(Thread.java:619) My mysql database shows no tables created. (I don't think groovy's connected to mysql yet.) Things I've checked: mysql-connector-java-5.1.6.jar is in lib directory. I've tried grails clean I tried putting the dataSource info in the development environment (I haven't graduated to test or prod yet), but it seemed to make no difference. The stdout shows I'm using development env. I've googled for solutions, but the only solution I've found is when people don't change the test or production environments.

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• LINQ - Querying a list filtered via a Many-to-Many reltionship

  - by user118190

  Please excuse the context of my question for I did not know how to exactly word it. To not complicate things further, here's my business requirement: "bring me back all the Employees where they belong in Department "X". So when I view this, it will display all of the Employees that belong to this Department. Here's my environment: Silverlight 3 with Entity Framework 1.0 and WCF Data Services 1.0. I am able to load and bind all kinds of lists (simple), no problem. I don't feel that my environment matters and that's why I feel it is a LINQ question more than the technologies. My question is for scenarios where I have 3 tables linked, i.e. entities (collections). For example, I have this in my EDM: Employee--EmployeeProject--Project. Here's the table design from the Database: Employee (table1) ------------- EmployeeID (PK) FirstName other Attributes ... EmployeeProject (table2) ------------- EmployeeProjectID (PK) EmployeeID (FK) ProjectID (FK) AssignedDate other Attributes ... Project (table3) ------------- ProjectID (PK) Name other Attributes ... Here's the EDM design from Entity Framework: ------------------------ Employee (entity1) ------------------------ (Scalar Properties) ------------------- EmployeeID (PK) FirstName other Attributes ... ------------------- (Navigation Properties) ------------------- EmployeeProjects ------------------------ EmployeeProject (entity2) ------------------------ (Scalar Properties) ------------------- EmployeeProjectID (PK) AssignedDate other Attributes ... ------------------- (Navigation Properties) ------------------- Employee Project ------------------------ Project (entity3) ------------------------ (Scalar Properties) ------------------- ProjectID (PK) Name other Attributes ... ------------------- (Navigation Properties) ------------------- EmployeeProjects So far, I have only been able to do: var filteredList = Context.Employees .Where(e => e.EmployeeProjects.Where(ep => ep.Project.Name == "ProjectX")) NOTE: I have updated the syntax of the query after John's post. As you can see, I can only query, the related entity (EmployeeProjects). All I want is being able to filter to Project from the Employee entity. Thanks for any advice.

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• Why is using a common-lookup table to restrict the status of entity wrong?

  - by FreshCode

  According to Five Simple Database Design Errors You Should Avoid by Anith Sen, using a common-lookup table to store the possible statuses for an entity is a common mistake. Why is this wrong? I disagree that it's wrong, citing the example of jobs at a repair service with many possible statuses that generally have a natural flow, eg.: Booked In Assigned to Technician Diagnosing problem Waiting for Client Confirmation Repaired & Ready for Pickup Repaired & Couriered Irreparable & Ready for Pickup Quote Rejected Arguably, some of these statuses can be normalised to tables like Couriered Items, Completed Jobs and Quotes (with Pending/Accepted/Rejected statuses), but that feels like unnecessary schema complication. Another common example would be order statuses that restrict the status of an order, eg: Pending Completed Shipped Cancelled Refunded The status titles and descriptions are in one place for editing and are easy to scaffold as a drop-down with a foreign key for dynamic data applications. This has worked well for me in the past. If the business rules dictate the creation of a new order status, I can just add it to OrderStatus table, without rebuilding my code.

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• Problem importing Oracle .dmp file

  - by BitFiddler

  So I have looked at all the suggested ways of importing .dmp files and non of them seem to answer this question: where does the data go once you import it? Context: I created a user like so: SQL> create user IMPORTER identified by "12345"; SQL> grant connect, unlimited tablespace, resource to IMPORTER; I then ran the 'imp' command as follows: C:\>imp system/password FROMUSER=OVIEDOE TOUSER=IMPORTER file=c:\database1.dmp Now there were 9 .dmp files, after each one it asked me for the next one and then I received the message "Import terminated successfully with warnings." The warning was: Warning: the objects were exported by OVIEDOE, not by you import done in WE8MSWIN1252 character set and AL16UTF16 NCHAR character set export client uses WE8ISO8859P1 character set (possible charset conversion) IMP-00046: using FILESIZE value from export file of 2147483648 Now it says it was terminated successfully so my assumption (I am new to oracle so this may be wrong) is that the data was loaded. However, when I use SQL developer to connect to the database and look under the 'tables' node under the IMPORTER user, there is nothing there. What is going on? Did the data load? If so, where can I find it?

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• SQL SERVER FOR XML SYNTAX

  - by Raj73

  How can I get an output as follows using FOR XML / sql query. I am not sure how I can get the Column Values as Elements instead of the tables' column Names. I am using sql server 2005 I HAVE TABLE SCEMA AS FOLLOWS CREATE TABLE PARENT ( PID INT, PNAME VARCHAR(20) ) CREATE TABLE CHILD ( PID INT, CID INT, CNAME VARCHAR(20) ) CREATE TABLE CHILDVALUE ( CID INT, CVALUE VARCHAR(20) ) INSERT INTO PARENT VALUES (1, 'SALES1') INSERT INTO PARENT VALUES (2, 'SALES2') INSERT INTO CHILD VALUES (1, 1, 'FOR01') INSERT INTO CHILD VALUES (1, 2, 'FOR02') INSERT INTO CHILD VALUES (2, 3, 'FOR03') INSERT INTO CHILD VALUES (2, 4, 'FOR04') INSERT INTO CHILDVALUE VALUES (1, '250000') INSERT INTO CHILDVALUE VALUES (2, '400000') INSERT INTO CHILDVALUE VALUES (3, '500000') INSERT INTO CHILDVALUE VALUES (4, '800000') The Output I am looking for is as follows <SALE1> <FOR01>250000</FOR01> <FOR02>400000</FOR02> </SALE1> <SALE2> <FOR03>500000</FOR03> <FOR04>800000</FOR04> </SALE2>

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• How create single HTML file to viewed in Excel with multiple sheets?

  - by Dmitry Nelepov

  I want know, is it possible create single HTML file wich (after chaging extension to xls) when opened at Excel will parsed to multiple sheets. Little example i got file test.xls with contents <html> <body> <table> <tr> <td> 1 </td> <td> 2 </td> <td> 3 </td> <td> =sum(A1:C1) </td> </tr> </table> </body> </html> When i open this file at Excel i got one Sheet with calculated sum of cells A1 to C1 in A4=6 I wonder, it's possible create a HTML file wich containts multiple tables wich will be parsed as multiple sheets at Excel. Here Excel view of this file

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• php and mysql site design question

  - by Jacksta

  I am trying to build a website with mysql and php. This is the first site I have attempted so I want to write a little plan and get some feedback. The site allows users to add some text in a text field as a “comment”. Once the comment has been entered into the site it is added to the database where it can be voted for by other users. When a new comment has been added to the database it needs to create a new page, e.g. www.xxxxx.com/commentname or www.xxxxxx.com/?id=99981. There will be a list of "Comments" in the database along with the number of votes for each comment. The home page will have two functions. 1) Allow users to add a "comment" 2) Display two tables, each with 20 rows containing most "popular comments" and "recent comments" Each comment will generate its one page where the comment will be displayed. Here users can read the comment and Vote for the comment if they wish. Please help me out by explaining how to do the following. -Generate a new page whenever a comment is added to the database -Add a vote to the vote count in the comment database. -Display the top 20 most popular comments as per number of votes.

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• Database schema for Product Properties

  - by Chemosh

  As so many people I'm looking for a Products /Product Properties database schema. I'm using Ruby on Rails and (Thinking) Sphinx for faceted searches. Requirements: Adding new product types and their options should not require a change to the database schema Support faceted searches using Sphinx. Solutions I've come across: (See Bill Karwin's answer) Option 1: Single Table Inheritance Not an option really. The table would contain way to many columns. Option 2: Class Table Inheritance Ruby on Rails caches the database schema on start-up which means a restart whenever a new type of product is introduced. If you have a size able product catalog this could mean hundreds of tables. Option 3: Serialized LOB Kills being able to do faceted searches without heavy application logic. Option 4: Entity-Attribute-Value For testing purposes, EAV worked fine. However it could quickly become a mess and a maintenance hell as you add more and more options (e.g. when an option increase the prices or delivery time). What option should I go with? What other solutions are out there? Is there a silver bullet (ha) I overlooked?

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• MySQL query puzzle - finding what WOULD have been the most recent date

  - by Hank

  I've looked all over and haven't yet found an intelligent way to handle this, though I feel sure one is possible: One table of historical data has quarterly information: CREATE TABLE Quarterly ( unique_ID INT UNSIGNED NOT NULL, date_posted DATE NOT NULL, datasource TINYINT UNSIGNED NOT NULL, data FLOAT NOT NULL, PRIMARY KEY (unique_ID)); Another table of historical data (which is very large) contains daily information: CREATE TABLE Daily ( unique_ID INT UNSIGNED NOT NULL, date_posted DATE NOT NULL, datasource TINYINT UNSIGNED NOT NULL, data FLOAT NOT NULL, qtr_ID INT UNSIGNED, PRIMARY KEY (unique_ID)); The qtr_ID field is not part of the feed of daily data that populated the database - instead, I need to retroactively populate the qtr_ID field in the Daily table with the Quarterly.unique_ID row ID, using what would have been the most recent quarterly data on that Daily.date_posted for that data source. For example, if the quarterly data is 101 2009-03-31 1 4.5 102 2009-06-30 1 4.4 103 2009-03-31 2 7.6 104 2009-06-30 2 7.7 105 2009-09-30 1 4.7 and the daily data is 1001 2009-07-14 1 3.5 ?? 1002 2009-07-15 1 3.4 && 1003 2009-07-14 2 2.3 ^^ then we would want the ?? qtr_ID field to be assigned '102' as the most recent quarter for that data source on that date, and && would also be '102', and ^^ would be '104'. The challenges include that both tables (particularly the daily table) are actually very large, they can't be normalized to get rid of the repetitive dates or otherwise optimized, and for certain daily entries there is no preceding quarterly entry. I have tried a variety of joins, using datediff (where the challenge is finding the minimum value of datediff greater than zero), and other attempts but nothing is working for me - usually my syntax is breaking somewhere. Any ideas welcome - I'll execute any basic ideas or concepts and report back.

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• Combining two-part SQL query into one query

  - by user332523

  Hello, I have a SQL query that I'm currently solving by doing two queries. I am wondering if there is a way to do it in a single query that makes it more efficient. Consider two tables: Transaction_Entries table and Transactions, each one defined below: Transactions - id - reference_number (varchar) Transaction_Entries - id - account_id - transaction_id (references Transactions table) Notes: There are multiple transaction entries per transaction. Some transactions are related, and will have the same reference_number string. To get all transaction entries for Account X, then I would do SELECT E.*, T.reference_number FROM Transaction_Entries E JOIN Transactions T ON (E.transaction_id=T.id) where E.account_id = X The next part is the hard part. I want to find all related transactions, regardless of the account id. First I make a list of all the unique reference numbers I found in the previous result set. Then for each one, I can query all the transactions that have that reference number. Assume that I hold all the rows from the previous query in PreviousResultSet UniqueReferenceNumbers = GetUniqueReferenceNumbers(PreviousResultSet) // in Java foreach R in UniqueReferenceNumbers // in Java SELECT * FROM Transaction_Entries where transaction_id IN (SELECT * FROM Transactions WHERE reference_number=R Any suggestions how I can put this into a single efficient query?

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• ASP.NET MVC - Wrong redirecting, how to debug?

  - by Xorty

  I am stuck with redirecting problem in ASP.NET MVC project. I have mapped tables via LINQtoSQL and each has unique ID as primary key. I am implementing functionallity of 'CREATE'. Basically, after new value is added into SQL table (which means I pressed Save button), I want to be redirected to Details of this freshly added item. Here's little code how I am doing it : [AcceptVerbs(HttpVerbs.Post), Authorize] public ActionResult Create(Item item) { .... return RedirectToAction("Details", new { id = item.ItemID }); Trouble is, I am never redirected to Details view (I have Details.aspx view for items). When I check CallHierarchy in Visual Studio (2010 pro) the hierarchy is indeed little strange, like this : RedirectToAction(string,object) Calls To 'RedirectToAction' Create Calls To Create (no results) Calls From Create (methods of created instance. From there I'll get back to 'RedirectToAction' and to 'Calls to Create' and 'Calls From Create' etc. etc. - loop Edit Calls From 'RedirectToAction' Not supported I am looking for some tools or more specifically 'know how' (since VS probably has some tools) to debug this kind of situations. PS: rooting is default :"{controller}/{action}/{id}", Thanks

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• How to return ArrayList results from an IntentService

  - by gcl1

  I have an IntentService that loads up an ArrayList with data from a network source (AWS SDB tables). The ArrayList is in a global space -- accessible to both the calling Activity and the IntentService (like this: appState = ((App)getApplicationContext())). When the IntentService is done, it notifies the Activity through a ResultReceiver, and the Activity calls adapter.notifyDataChanged() to update the ListView. This solution works most of the time, ... but it violates the rule that only the UI thread should make changes to data underlying a ListView. So as it is, I sometimes get an error: "The content of the adapter has changed but ListView did not receive a notification." I think this must be a common situation. Please let me know if you have any suggestions or best practices for this problem. Here are three options I'm aware of: Keep the IntentService, and have it store the results in another "working" ArrayList, also in the global space. When the result is ready, the IntentService calls the ResultReceiver (on the UI thread), which can then: a) copy the result to the ArrayList associated with the ListView, and b) call adapter.notifyDataChanged(). CONS: I don't like the idea of putting temp/working data in a global space, and copying the result list seems inefficient. Keep the IntentService, and have it pass the results back through a bundle loaded with a ParcelableArrayList. CONS: I'm not sure if this approach would scale for very large result sets. It also requires copying the result list. Switch to a Service which builds a local copy of the result list. Have the Activity directly access the address space of the Service in order to read the result list. CON: Still requires copying results to the ArrayList associated with the ListView. Thank you.

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• Managing libraries and imports in a programming language

  - by sub

  I've created an interpreter for a stupid programming language in C++ and the whole core structure is finished (Tokenizer, Parser, Interpreter including Symbol tables, core functions, etc.). Now I have a problem with creating and managing the function libraries for this interpreter (I'll explain what I mean with that later) So currently my core function handler is horrible: // Simplified version myLangResult SystemFunction( name, argc, argv ) { if ( name == "print" ) { if( argc < 1 ) { Error('blah'); } cout << argv[ 0 ]; } else if ( name == "input" ) { if( argc < 1 ) { Error('blah'); } string res; getline( cin, res ); SetVariable( argv[ 0 ], res ); } else if ( name == "exit ) { exit( 0 ); } And now think of each else if being 10 times more complicated and there being 25 more system functions. Unmaintainable, feels horrible, is horrible. So I thought: How to create some sort of libraries that contain all the functions and if they are imported initialize themselves and add their functions to the symbol table of the running interpreter. However this is the point where I don't really know how to go on. What I wanted to achieve is that there is e.g.: an (extern?) string library for my language, e.g.: string, and it is imported from within a program in that language, example: import string myString = "abcde" print string.at( myString, 2 ) # output: c My problems: How to separate the function libs from the core interpreter and load them? How to get all their functions into a list and add it to the symbol table when needed? What I was thinking to do: At the start of the interpreter, as all libraries are compiled with it, every single function calls something like RegisterFunction( string namespace, myLangResult (*functionPtr) ); which adds itself to a list. When import X is then called from within the language, the list built with RegisterFunction is then added to the symbol table. Disadvantages that spring to mind: All libraries are directly in the interpreter core, size grows and it will definitely slow it down.

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