temporary tables - Page 359

In mysql, is "explain ..." always safe?

- by tye

If I allow a group of users to submit "explain $whatever" to mysql (via Perl's DBI using DBD::mysql), is there anything that a user could put into $whatever that would make any database changes, leak non-trivial information, or even cause significant database load? If so, how? I know that via "explain $whatever" one can figure out what tables / columns exist (you have to guess names, though) and roughly how many records are in a table or how many records have a particular value for an indexed field. I don't expect one to be able to get any information about the contents of unindexed fields. DBD::mysql should not allow multiple statements so I don't expect it to be possible to run any query (just explain one query). Even subqueries should not be executed, just explained. But I'm not a mysql expert and there are surely features of mysql that I'm not even aware of. In trying to come up with a query plan, might the optimizer actual execute an expression in order to come up with the value that an indexed field is going to be compared against? explain select * from atable where class = somefunction(...) where atable.class is indexed and not unique and class='unused' would find no records but class='common' would find a million records. Might 'explain' evaluate somefunction(...)? And then could somefunction(...) be written such that it modifies data?

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Entity Framework not populating context

- by stimms

I'm just starting out with some entity framework exploration, I figured it was time to see what everybody was complaining about. I am running into an issue where the entities don't seem to be returning any of the object context. I generated the model from a database with three tables which link to one another. Courses Instructors CanTeach Relationships are as you would expect: a course can relate to multiple CanTeach entities and an instructor can also relate to multiple CanTeach entities. I also added an OData service to my project which also makes use of the same model. So I can run queries like from a in CanTeach where a.Instructor.FirstName == "Barry" select new { Name = a.Instructor.FirstName + " " + a.Instructor.LastName, Course = a.Course.Name} without issue against the OData endpoint using LINQPad. However when I do a simple query like public Instructor GetInstructorFromID(int ID) { return context.Instructors.Where(i => i.ID == ID).FirstOrDefault(); } The CanTeach list is empty. I know everything in EF is lazy loaded and it is possible that my context is out of scope by the time I look at the object context, however even trying to get the object context as soon as the query is run results in and empty object context. What am I doing wrong?

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How to fix this simple SQL query?

- by morpheous

I have a database with three tables: user_table country_table city_table I want to write ANSI SQL which will allow me to fetch all the user data (i.e. user details including the name of the country of the last school and the name of the city they live in now). The problem I am having is that I have to use a self join, and I am getting slightly confused. The schema is shown below: CREATE TABLE user_table (id int, first_name varchar(16), last_school_country_id int, city_id int); CREATE TABLE country_table (id int, name varchar(32)); CREATE TABLE city_table (id int, country_id int, name varchar(32)); This is the query I have come up with so far, but the results are wrong, and sometimes, the db engine (mySQL), asks me if I want to show all [HUGE NUMBER HERE] results - which makes me suspect that I am unintentionally creating a cartesian product somewhere. Can someone explain what is wrong with this SQL statement, and what I need to do to fix it? SELECT usr.id AS id, usr.first_name, ctry1.name as loc_country_name, ctry2.name as school_country_name, city.name as loc_city_name FROM user_table usr, country_table ctry1, country_table ctry2, city_table city WHERE usr.last_school_country_id=ctry2.id AND usr.city_id=city.id AND city.country_id=ctry1.id AND ctry1.id=ctry2.id;

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How can I make Access think there is a primary key

- by user3692757

I have a table and I'm trying to join it with another table, but it doesn't have a distinctive primary key. The two tables do share similarities, “Acct” and “Location”. If I could concatenate “Acct&Location” it would become a primary key, but Access won’t let me make a primary key from a calculation. I provided a small sample below. Each hospital has an “Acct”, but the “Acct” will show up once for each “Location”. How can I make join these in a relationship? I connected the two in a relationships and tried to “Enforce Referential Integrity”, but it indicated “No unique index found for the referenced field of the primary key”. Also, if I run a “Find UnMatched Query” it doesn’t find anything. I think its because I can’t make it realize that in combination “Acct” and “Location” can be perceived as primary keys when used in conjunction of each other. Acct 1 2 3 1 2 3 1 2 3| Location ABI ABI ABI NHO NHO NHO NTX NTX NTX I tried to load an image to illustrate it better, but I haven't made enough post.

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Looking for Simplified Overview of EJB3

- by sdoca

Hi I'm looking for a simplified overview of EJB3 components. I seem to understand most of the pieces of the puzzle, but can't quite get them to fit together in my brain as a full picture. I've developed numerous web applications (wars) that have been deployed on Tomcat before, but not a full-fledged EE application (ear). I would like the overview to be as generic as possible. I'm not looking for a tutorial on how to set up EJB3 on Glassfish built in NetBeans or some other vendor specific tutorial that's more about the IDE than the technology. I keep reading about Java, ejb-jar, web and ear modules but am not clear on what these different modules contain and how to use them to put together my app. In my case, I want to write a simple database CRUD web application. The first step is simple; create entity classes that model the database tables my app will be using. I plan on using annotations. Should I create a jar that contains just these enity classes? Is this the ejb-jar module (sometimes referred to as the Java module)? Next, I'll need some business logic classes that make use of the entity classes. These are the session beans (stateless or stateful) correct? Should these be packaged in the same jar as the entity classes or a separate jar? Finally, I'll need some sort of web interface (I'll be creating a JSF portlet) application that makes use of the both the session and entity beans. Together with the above jar(s), this will be my war? Assuming the above to be correct, what is involved in creating an ear? Forgive me if this post is vague, but I'm having a hard time defining what it is I don't understand. Thanks for any help!

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.net printing multiple reports in one document (architecture question)

- by LawsonM

I understand how to print a single document via the PrintDocument class. However, I want to print multiple reports in one document. Each "report" will consist of charts, tables, etc. I want to have two reports per page. I've studied the few examples I can find on how to combine multiple documents into one; however, they always seem to work by creating a collection of objects (e.g. customer or order) that are then iterated over and drawn in the OnPrintPage method. My problem and hence the "architecture" question is that I don't want to cache the objects required to produce the report since they are very large and memory intensive. I'd simply like the resulting "report". One thought I had was to print the report to a metafile, cache that instead in a "MultiplePrintDocument" class and then position those images appropriately two to a page in the OnPrintPage method. I think this would be a lot more efficient and scalable in my case. But I'm not a professional programmer and can't figure out if I'm barking up the wrong tree here. I think the Graphics.BeginContainer and Graphics.Save methods might be relevant, but can't figure out how to implement or if there is a better way. Any pointers would be greatly appreciated.

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Forming triangles from points and relations

- by SiN

Hello, I want to generate triangles from points and optional relations between them. Not all points form triangles, but many of them do. In the initial structure, I've got a database with the following tables: Nodes(id, value) Relations(id, nodeA, nodeB, value) Triangles(id, relation1_id, relation2_id, relation3_id) In order to generate triangles from both nodes and relations table, I've used the following query: INSERT INTO Triangles SELECT t1.id, t2.id , t3.id, FROM Relations t1, Relations t2, Relations t3 WHERE t1.id < t2.id AND t3.id > t1.id AND ( t1.nodeA = t2.nodeA AND (t3.nodeA = t1.nodeB AND t3.nodeB = t2.nodeB OR t3.nodeA = t2.nodeB AND t3.nodeB = t1.nodeB) OR t1.nodeA = t2.nodeB AND (t3.nodeA = t1.nodeB AND t3.nodeB = t2.nodeA OR t3.nodeA = t2.nodeA AND t3.nodeB = t1.nodeB) ) It's working perfectly on small sized data. (~< 50 points) In some cases however, I've got around 100 points all related to each other which leads to thousands of relations. So when the expected number of triangles is in the hundreds of thousands, or even in the millions, the query might take several hours. My main problem is not in the select query, while I see it execute in Management Studio, the returned results slow. I received around 2000 rows per minute, which is not acceptable for my case. As a matter of fact, the size of operations is being added up exponentionally and that is terribly affecting the performance. I've tried doing it as a LINQ to object from my code, but the performance was even worse. I've also tried using SqlBulkCopy on a reader from C# on the result, also with no luck. So the question is... Any ideas or workarounds?

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MySQL - What is wrong with this query or my database? Terrible performance.

- by Moss

SELECT * from `employees` a LEFT JOIN (SELECT phone1 p1, count(*) c, FROM `employees` GROUP BY phone1) b ON a.phone1 = b.p1; I'm not sure if it is this query in particular that has the problem. I have been getting terrible performance in general with this database. The table in question has 120,000 rows. I have tried this particular query remotely and locally with the MyISAM and InnoDB engines, with different types of joins, and with and without an index on phone1. I can get this to complete in about 4 minutes on a 10,000 row table successfully but performance drops exponentially with larger tables. Remotely it will lose connection to the server and locally it brings my system to its knees and seems to go on forever. This query is only a smaller step I was trying to do when a larger query couldn't complete. Maybe I should explain the whole scenario. I have one big flat ugly table that lists a bunch of people and their contact info and the info of the companies they work for. I'm trying to normalize the database and intelligently determine which phone numbers apply to individual people and which apply to an office location. My reasoning is that if a phone number occurs multiple times and the number of occurrence equals the number of times that the street address it is attached to occurs then it must be an office number. So the first step is to count each phone number grouping by phone number. Normally if you just use COUNT()...GROUP BY it will only list the first record it finds in that group so I figured I have to join the full table to the count table where the phone number matches. This does work but as I said I can't successfully complete it on any table much larger than 10,000 rows. This seems pathetic and this doesn't seem like a crazy query to do. Is there a better way to achieve what I want or do I have to break my large table into 12 pieces or is there something wrong with the table or db?

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Advice on Linq to SQL mapping object design

- by fearofawhackplanet

I hope the title and following text are clear, I'm not very familiar with the correct terms so please correct me if I get anything wrong. I'm using Linq ORM for the first time and am wondering how to address the following. Say I have two DB tables: User ---- Id Name Phone ----- Id UserId Model The Linq code generator produces a bunch of entity classes. I then write my own classes and interfaces which wrap these Linq classes: class DatabaseUser : IUser { public DatabaseUser(User user) { _user = user; } public Guid Id { get { return _user.Id; } } ... etc } so far so good. Now it's easy enough to find a users phones from Phones.Where(p => p.User = user) but surely comsumers of the API shouldn't need to be writing their own Linq queries to get at data, so I should wrap this query in a function or property somewhere. So the question is, in this example, would you add a Phones property to IUser or not? In other words, should my interface specifically be modelling my database objects (in which case Phones doesn't belong in IUser), or are they actually simply providing a set of functions and properties which are conceptually associated with a User (in which case it does)? There seems drawbacks to both views, but I'm wondering if there is a standard approach to the problem. Or just any general words of wisdom you could share. My first thought was to use extension methods but in fact that doesn't work in this case.

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Best practices for (over)using Azure queues

- by John

Hi, I'm in the early phases of designing an Azure-based application. One of the things that attracts me to Azure is the scalability, given the variability of the demand I'm likely to expect. As such I'm trying to keep things loosely coupled so I can add instances when I need to. The recommendations I've seen for architecting an application for Azure include keeping web role logic to a minimum, and having processing done in worker roles, using queues to communicate and some sort of back-end store like SQL Azure or Azure Tables. This seems like a good idea to me as I can scale up either or both parts of the application without any issue. However I'm curious if there are any best practices (or if anyone has any experiences) for when it's best to just have the web role talk directly to the data store vs. sending data by the queue? I'm thinking of the case where I have a simple insert to do from the web role - while I could set this up as a message, send it on the queue, and have a worker role pick it up and do the insert, it seems like a lot of double-handling. However I also appreciate that it may be the case that this is better in the long run, in case the web role gets overwhelmed or more complex logic ends up being required for the insert. I realise this might be a case where the answer is "it depends entirely on the situation, check your perf metrics" - but if anyone has any thoughts I'd be very appreciative! Thanks John

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Hibernate NamingStrategy implementation that maintains state between calls

- by Robert Petermeier

Hi, I'm working on a project where we use Hibernate and JBoss 5.1. We need our entity classes to be mapped to Oracle tables that follow a certain naming convention. I'd like to avoid having to specify each table and column name in annotations. Therefore, I'm currently considering implementing a custom implementation of org.hibernate.cfg.NamingStrategy. The SQL naming conventions require the name of columns to have a suffix that is equivalent to a prefix of the table name. If there is a table "T100_RESOURCE", the ID column would have to be named "RES_ID_T100". In order to implement this in a NamingStrategy, the implementation would have to maintain state, i.e. the current class name it is creating the mappings for. It would rely on Hibernate to always call classToTableName() before propertyToColumnName() and to determine all column names by calling propertyToColumnName() before the next call to classToTableName() Is it safe to do that or are there situations where Hibernate will mix things up? I am not thinking of problems through multiple threads here (which can be solved by keeping the last class name in a ThreadLocal) but also of Hibernate deliberately calling this out of order in certain circumstances. For example Hibernate asking for mappings of three properties of class A, then one of class B, then again more attributes of class A.

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PL-SQL - Two statements with begin and end, run fine seperately but not together?

- by Twiss

Hi all, Just wondering if anyone can help with this, I have two PLSQL statements for altering tables (adding extra fields) and they are as follows: -- Make GC_NAB field for Next Action By Dropdown begin if 'VARCHAR2' = 'NUMBER' and length('VARCHAR2')>0 and length('')>0 then execute immediate 'alter table "SERVICEMAIL6"."ETD_GUESTCARE" add(GC_NAB VARCHAR2(10, ))'; elsif ('VARCHAR2' = 'NUMBER' and length('VARCHAR2')>0 and length('')=0) or 'VARCHAR2' = 'VARCHAR2' then execute immediate 'alter table "SERVICEMAIL6"."ETD_GUESTCARE" add(GC_NAB VARCHAR2(10))'; else execute immediate 'alter table "SERVICEMAIL6"."ETD_GUESTCARE" add(GC_NAB VARCHAR2)'; end if; commit; end; -- Make GC_NABID field for Next Action By Dropdown begin if 'NUMBER' = 'NUMBER' and length('NUMBER')>0 and length('')>0 then execute immediate 'alter table "SERVICEMAIL6"."ETD_GUESTCARE" add(GC_NABID NUMBER(, ))'; elsif ('NUMBER' = 'NUMBER' and length('NUMBER')>0 and length('')=0) or 'NUMBER' = 'VARCHAR2' then execute immediate 'alter table "SERVICEMAIL6"."ETD_GUESTCARE" add(GC_NABID NUMBER())'; else execute immediate 'alter table "SERVICEMAIL6"."ETD_GUESTCARE" add(GC_NABID NUMBER)'; end if; commit; end; When I run these two queries seperately, no problems. However, when run together as shown above, Oracle gives me an error when it starts the second statement: Error report: ORA-06550: line 15, column 1: PLS-00103: Encountered the symbol "BEGIN" 06550. 00000 - "line %s, column %s:\n%s" *Cause: Usually a PL/SQL compilation error. *Action: I'm assuming that this means the first statement is not terminated properly... is there anything I should put inbetween the statements to make it work properly? Thanks in advance everyone!

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Query returning related assets

- by GMo

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ASP.Net MVC - how can I easily serialize query results to a database?

- by Mortanis

I've been working on a little property search engine while I learn ASP.Net MVC. I've gotten the results from various property database tables and sorted them into a master generic property response. The search form is passed via Model Binding and works great. Now, I'd like to add pagination. I'm returning the chunk of properties for the current page with .Skip() and .Take(), and that's working great. I have a SearchResults model that has the paged result set and various other data like nextPage and prevPage. Except, I no longer have the original form of course to pass to /Results/2. Previously I'd have just hidden a copy of the form and done a POST each time, but it seems inelegant. I'd like to serialize the results to my MS SQL database and return a unique key for that results set - this also helps with a "Send this query to a friend!" link. Killing two birds with one stone. Is there an easy way to take an IQueryable result set that I have, serialize it, stick it into the DB, return a unique key and then reverse the process with said key? I'm using Linq to SQL currently on a MS SQL Express install, though in production it'll be on MS SQL 2008.

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Exit and rollback everything in script on error

- by Jan W.

Hey guys ! I'm in a bit of a pickle here. I have a TSQL script that does a lot of database structure adjustments but it's not really safe to just let it go through when something fails. to make things clear: using MS SQL 2005 it's NOT a stored procedure, just a script file (.sql) what I have is something in the following order BEGIN TRANSACTION ALTER Stuff GO CREATE New Stuff GO DROP Old Stuff GO IF @@ERROR != 0 BEGIN PRINT 'Errors Found ... Rolling back' ROLLBACK TRANSACTION RETURN END ELSE PRINT 'No Errors ... Committing changes' COMMIT TRANSACTION just to illustrate what I'm working with ... can't go into specifics now, the problem ... When I introduce an error (to test if things get rolled back), I get a statement that the ROLLBACK TRANSACTION could not find a corresponding BEGIN TRANSACTION. This leads me to believe that something when REALLY wrong and the transaction was already killed. what I also noticed is that the script didn't fully quit on error and thus DID try to execute every statement after the error occured. (I noticed this when new tables showed up when I wasn't expecting them because it should have rollbacked) any help in this department is welcome if more speficics are needed, ask! greetz

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sql server - framework 4 - IIS 7 weird sort from db to page

- by ila

I am experiencing a strange behavior when reading a resultset from database in a calling method. The sort of the rows is different from what the database should return. My farm: - database server: sql server 2008 on a WinServer 2008 64 bit - web server: a couple of load balanced WinServer 2008 64 bit running IIS 7 The application runs on a v4.0 app pool, set to enable 32bit applications Here's a description of the problem: - a stored procedure is called, that returns a resultset sorted on a particular column - I can see thru profiler the call to the SP, if I run the statement I see correct sorting - the calling page gets the results, and before any further elaboration logs the rows immediately after the SP execution - the results are in a completely different order (I cannot even understand if they are sorted in any way) Some details on the Stored Procedure: - it is called by code using a SqlDatAdapter - it has also an output value (a count of the rows) that is read correctly - which sort field is to be used is passed as a parameter - makes use of temp tables to collect data and perform the desired sort Any idea on what I could check? Same code and same database work correctly in a test environment, 32 bit and not load balanced.

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Geohashing - recursively find neighbors of neighbors

- by itsme

I am now looking for an elegant algorithm to recursively find neighbors of neighbors with the geohashing algorithm (http://www.geohash.org). Basically take a central geohash, and then get the first 'ring' of same-size hashes around it (8 elements), then, in the next step, get the next ring around the first etc. etc. Have you heard of an elegant way to do so? Brute force could be to take each neighbor and get their neighbors simply ignoring the massive overlap. Neighbors around one central geohash has been solved many times (here e.g. in Ruby: http://github.com/masuidrive/pr_geohash/blob/master/lib/pr_geohash.rb) Edit for clarification: Current solution, with passing in a center key and a direction, like this (with corresponding lookup-tables): def adjacent(geohash, dir) base, lastChr = geohash[0..-2], geohash[-1,1] type = (geohash.length % 2)==1 ? :odd : :even if BORDERS[dir][type].include?(lastChr) base = adjacent(base, dir) end base + BASE32[NEIGHBORS[dir][type].index(lastChr),1] end (extract from Yuichiro MASUI's lib) I say this approach will get ugly soon, because directions gets ugly once we are in ring two or three. The algorithm would ideally simply take two parameters, the center area and the distance from 0 being the center geohash only (["u0m"] and 1 being the first ring made of 8 geohashes of the same size around it (= [["u0t", "u0w"], ["u0q", "u0n"], ["u0j", "u0h"], ["u0k", "u0s"]]). two being the second ring with 16 areas around the first ring etc. Do you see any way to deduce the 'rings' from the bits in an elegant way?

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Entity Framework 1:1 Relationship Identity Colums

- by Hupperware

I cannot for the life of me get two separate tables to save with a relationship and two identity columns. I keep getting errors like A dependent property in a ReferentialConstraint is mapped to a store-generated column. Column: 'OlsTerminalId'. I can't imagine that this setup is abnormal. [DataContract] public class OlsData { private static readonly DateTime theUnixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc); [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int OlsDataId { get; set; } [DataMember(Name = "id")] public int Id { get; set; } public DateTime Timestamp { get; set; } [DataMember(Name = "created")] [NotMapped] public double Created { get { return (Timestamp - theUnixEpoch).TotalMilliseconds; } set { Timestamp = theUnixEpoch.AddMilliseconds(value); } } [InverseProperty("OlsData")] [DataMember(Name = "terminal")] public virtual OlsTerminal OlsTerminal { get; set; } } [DataContract] public class OlsTerminal { [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int OlsTerminalId { get; set; } public int OlsDataId { get; set; } [DataMember(Name = "account")] [NotMapped] public virtual OlsAccount OlsAccount { get; set; } [DataMember(Name = "terminalId")] public string TerminalId { get; set; } [DataMember(Name = "merchantId")] public string MerchantId { get; set; } public virtual OlsData OlsData { get; set; } } public class OlsDataContext : DbContext { protected override void OnModelCreating(DbModelBuilder aModelBuilder) { aModelBuilder.Conventions.Remove<PluralizingTableNameConvention>(); } public OlsDataContext(string aConnectionString) : base(aConnectionString) {} public DbSet<OlsData> OlsData { get; set; } public DbSet<OlsTerminal> OlsTerminal { get; set; } public DbSet<OlsAccount> OlsAccount { get; set; } }

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What might be causing this Rails method error?

- by Trip

My error: Notice the undefined method '-@' . This is for a sort by. All sorts on one page break, but all the sorts on other pages use the same helper and do not break. Does it allude to something obvious? Processing OrganizationsController#search (for ::1 at 2010-05-13 15:42:01) [GET] Parameters: {"action"=>"search", "controller"=>"organizations", "direction"=>"desc", "_"=>"1273779721464", "order_by"=>"published_at"} SQL (0.5ms) SHOW TABLES Organization Columns (2.2ms) SHOW FIELDS FROM `organizations` NoMethodError (undefined method `-@' for #<Array:0x2f88cc8>): app/controllers/organizations_controller.rb:190:in `search' sunspot (1.0.5) lib/sunspot/util.rb:84:in `call' sunspot (1.0.5) lib/sunspot/util.rb:84:in `instance_eval_or_call' sunspot (1.0.5) lib/sunspot/search.rb:200:in `build' sunspot (1.0.5) lib/sunspot/session.rb:45:in `new_search' sunspot (1.0.5) lib/sunspot/session.rb:53:in `search' sunspot (1.0.5) lib/sunspot/session_proxy/abstract_session_proxy.rb:11:in `search' sunspot (1.0.5) lib/sunspot.rb:323:in `search' app/controllers/organizations_controller.rb:183:in `search' haml (2.2.2) [v] rails/./lib/sass/plugin/rails.rb:19:in `process' lib/flash_session_cookie_middleware.rb:14:in `call' vendor/gems/hoptoad_notifier-2.2.2/lib/hoptoad_notifier/rack.rb:27:in `call' /usr/local/lib/ruby/1.8/webrick/httpserver.rb:104:in `service' /usr/local/lib/ruby/1.8/webrick/httpserver.rb:65:in `run' /usr/local/lib/ruby/1.8/webrick/server.rb:173:in `start_thread' /usr/local/lib/ruby/1.8/webrick/server.rb:162:in `start' /usr/local/lib/ruby/1.8/webrick/server.rb:162:in `start_thread' /usr/local/lib/ruby/1.8/webrick/server.rb:95:in `start' /usr/local/lib/ruby/1.8/webrick/server.rb:92:in `each' /usr/local/lib/ruby/1.8/webrick/server.rb:92:in `start' /usr/local/lib/ruby/1.8/webrick/server.rb:23:in `start' /usr/local/lib/ruby/1.8/webrick/server.rb:82:in `start' Rendered rescues/_trace (68.5ms) Rendered rescues/_request_and_response (0.6ms) Rendering rescues/layout (internal_server_error)

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How to make Spring load a JDBC Driver BEFORE initializing Hibernate's SessionFactory?

- by Bill_BsB

I'm developing a Spring(2.5.6)+Hibernate(3.2.6) web application to connect to a custom database. For that I have custom JDBC Driver and Hibernate Dialect. I know for sure that these custom classes work (hard coded stuff on my unit tests). The problem, I guess, is with the order on which things get loaded by Spring. Basically: Custom Database initializes Spring load beans from web.xml Spring loads ServletBeans(applicationContext.xml) Hibernate kicks in: shows version and all the properties correctly loaded. Hibernate's HbmBinder runs (maps all my classes) LocalSessionFactoryBean - Building new Hibernate SessionFactory DriverManagerConnectionProvider - using driver: MyCustomJDBCDriver at CustomDBURL I get a SQLException: No suitable driver found for CustomDBURL Hibernate loads the Custom Dialect My CustomJDBCDriver finally gets registered with DriverManager (log messages) SettingsFactory runs SchemaExport runs (hbm2ddl) I get a SQLException: No suitable driver found for CustomDBURL (again?!) Application get successfully deployed but there are no tables on my custom Database. Things that I tried so far: Different techniques for passing hibernate properties: embedded in the 'sessionFactory' bean, loaded from a hibernate.properties file. Nothing worked but I didn't try with hibernate.cfg.xml file neither with a dataSource bean yet. MyCustomJDBCDriver has a static initializer block that registers it self with the DriverManager. Tried different combinations of lazy initializing (lazy-init="true") of the Spring beans but nothing worked. My custom JDBC driver should be the first thing to be loaded - not sure if by Spring but...! Can anyone give me a solution for this or maybe a hint for what else I could try? I can provide more details (huge stack traces for instance) if that helps. Thanks in advance.

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Entity and N-Tier architecture in C#

- by acadia

Hello, I have three tables as shown below Emp ---- empID int empName deptID empDetails ----------- empDetailsID int empID int empDocuments -------------- docID empID docName docType I am creating a entity class so that I can use n-tier architecture to do database transactions etc in C#. I started creating class for the same as shown below using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace employee { class emp { private int empID; private string empName; private int deptID; public int EmpID { get; set; } public string EmpName { get; set; } public int deptID { get; set; } } } My question is as empDetails and empDocuments are related to emp by empID. How do I have those in my emp class. I would appreciate if you can direct me to an example. Thanks

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Self organizing layouts

- by user613326

Quite a while ago i was more in websites building then i am now. In my time there where huge debates about what to use; tables or pure CSS alternatives. I went out of the webdesigning, but now an old question re-surfaces. What i would like to create is a web page design that depending on screensize, would self organize the page into columns, so that for example on a PDA it would show 1 column On an old computer monitor, it would show 2 colomns, and on a widescreen laptop it would show 3 columns. I forgot how this was called and how it was done in the past, it had to do with XML and storing data seperate from design (if i remember well), perhaps these days better methods exist to do that, does this, anyone ring this a bell ? Also i note a lot is possible with Jquery and and brouwser depending webkits. But i need to make sure that it would run on all (modern) brouwsers : Iexplorer, Firefox, chrome And Jquery is nice too, but i am kinda woried that some day one of these brouwser vendors decides that jscript like java isnt enabled by default (or is that very unlikely ?)11 Perhaps someone can point me to a method that is the prefered way to do this.

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Linq. Help me tune this!

- by dtrick

I have a linq query that is causing some timeout issues. Basically, I have a query that is returning the top 100 results from a table that has approximately 500,000 records. Here is the query: using (var dc = CreateContext()) { var accounts = string.IsNullOrEmpty(searchText) ? dc.Genealogy_Accounts .Where(a => a.Genealogy_AccountClass.Searchable) .OrderByDescending(a => a.ID) .Take(100) : dc.Genealogy_Accounts .Where(a => (a.Code.StartsWith(searchText) || a.Name.StartsWith(searchText)) && a.Genealogy_AccountClass.Searchable) .OrderBy(a => a.Code) .Take(100); return accounts.Select(a => } } Oddly enough it is the first linq query that is causing the timeout. I thought that by doing a 'Take' we wouldn't need to scan all 500k of records. However, that must be what is happening. I'm guessing that the join to find what is 'searchable' is causing the issue. I'm not able to denormalize the tables... so I'm wondering if there is a way to rewrite the linq query to get it to return quicker... or if I should just write this query as a Stored Procedure (and if so, what might it look like). Thanks.

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Matching on search attributes selected by customer on front end

- by CodeNinja1974

I have a method in a class that allows me to return results based on a certain set of Customer specified criteria. The method matches what the Customer specifies on the front end with each item in a collection that comes from the database. In cases where the customer does not specify any of the attributes, the ID of the attibute is passed into the method being equal to 0 (The database has an identity on all tables that is seeded at 1 and is incremental). In this case that attribute should be ignored, for example if the Customer does not specify the Location then customerSearchCriteria.LocationID = 0 coming into the method. The matching would then match on the other attributes and return all Locations matching the other attibutes, example below: public IEnumerable<Pet> FindPetsMatchingCustomerCriteria(CustomerPetSearchCriteria customerSearchCriteria) { if(customerSearchCriteria.LocationID == 0) { return repository.GetAllPetsLinkedCriteria() .Where(x => x.TypeID == customerSearchCriteria.TypeID && x.FeedingMethodID == customerSearchCriteria.FeedingMethodID && x.FlyAblityID == customerSearchCriteria.FlyAblityID ) .Select(y => y.Pet); } } The code for when all criteria is specified is shown below: private PetsRepository repository = new PetsRepository(); public IEnumerable<Pet> FindPetsMatchingCustomerCriteria(CustomerPetSearchCriteria customerSearchCriteria) { return repository.GetAllPetsLinkedCriteria() .Where(x => x.TypeID == customerSearchCriteria.TypeID && x.FeedingMethodID == customerSearchCriteria.FeedingMethodID && x.FlyAblityID == customerSearchCriteria.FlyAblityID && x.LocationID == customerSearchCriteria.LocationID ) .Select(y => y.Pet); } I want to avoid having a whole set of if and else statements to cater for each time the Customer does not explicitly select an attribute of the results they are looking for. What is the most succint and efficient way in which I could achieve this?

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How to programmatically set the text of a cell of database in VB.Net?

- by manuel

I have a Microsoft Access database file connected to VB.NET. In the database table, I have a 'No.' and a 'Status' column. Then I have a textbox where I can input an integer. I also have a button, which will change the data cell in 'Status' where 'No.' = txtTitleNo.Text(), when I click it. Let's say I want the 'Status' cell to be changed to "Reserved". What codes should I put in the BtnReserve_Click? Here is the code: Public Class theForm Dim con As New OleDb.OleDbConnection Dim ds As New DataSet Dim daTitles As OleDb.OleDbDataAdapter Private Sub theForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load con.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=|DataDirectory|\db1.mdb" con.Open() daTitles = New OleDb.OleDbDataAdapter("SELECT * FROM Titles", con) daTitles.Fill(ds, "Titles") DataGridView1.DataSource = ds.Tables("Titles") DataGridView1.AutoResizeColumns() End Sub Private Sub BtnReserve_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnReserve.Click Dim daReserve As OleDb.OleDbCommand For i As Integer = 1 TReservedo DataGridView1.RowCount() If i = Val(txtTitleNo.Text()) Then daReserve = New OleDb.OleDbCommand("UPDATE Titles SET Status = 'Reserved' WHERE No = '" & i & "'", con) daReserve.ExecuteNonQuery() End If Next Dim cb As New OleDb.OleDbCommandBuilder(daTitles) daTitles.Update(ds, "Titles") End Sub This code still does not change the 'Status'. What should I do?

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