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• Mysterious constraints problem with SQL Server 2000

  - by Ramon

  Hi all I'm getting the following error from a VB NET web application written in VS 2003, on framework 1.1. The web app is running on Windows Server 2000, IIS 5, and is reading from a SQL server 2000 database running on the same machine. System.Data.ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. at System.Data.DataSet.FailedEnableConstraints() at System.Data.DataSet.EnableConstraints() at System.Data.DataSet.set_EnforceConstraints(Boolean value) at System.Data.DataTable.EndLoadData() at System.Data.Common.DbDataAdapter.FillFromReader(Object data, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords) at System.Data.Common.DbDataAdapter.FillFromCommand(Object data, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet) The problem appears when the web app is under a high load. The system runs fine when volume is low, but when the number of requests becomes high, the system starts rejecting incoming requests with the above exception message. Once the problem appears, very few requests actually make it through and get processed normally, about 2 in every 30. The vast majority of requests fail, until a SQL Server restart or IIS reset is performed. The system then start processing requests normally, and after some time it starts throwing the same error. The error occurs when a data adapter runs the Fill() method against a SELECT statement, to populate a strongly-typed dataset. It appears that the dataset does not like the data it is given and throws this exception. This error occurs on various SELECT statements, acting on different tables. I have regenerated the dataset and checked the relevant constraints, as well as the table from which the data is read. Both the dataset definition and the data in the table are fine. Admittedly, the hardware running both the web app and SQL Server 2000 is seriously outdated, considering the numbers of incoming requests it currently receives. The amount of RAM consumed by SQL Server is dynamically allocated, and at peak times SQL Server can consume up to 2.8 GB out of a total of 3.5 GB on the server. At first I suspected some sort of index or database corruption, but after running DBCC CHECKDB, no errors were found in the database. So now I'm wondering whether this error is a result of the hardware limitations of the system. Is it possible for SQL Server to somehow mess up the data it's supposed to pass to the dataset, resulting in constraint violation due to, say, data type/length mismatch? I tried accessing the RowError messages of the data rows in the retrieved dataset tables but I kept getting empty strings. I know that HasErrors = true for the datatables in question. I have not set the EnableConstraints = false, and I don't want to do that. Thanks in advance. Ray

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• Shared Variable Among Ruby Processes

  - by Jesse J

  I have a Ruby program that loads up two very large yaml files, so I can get some speed-up by taking advantage of the multiple cores by forking off some processes. I've tried looking, but I'm having trouble figuring how, or even if, I can share variables in different processes. The following code is what I currently have: @proteins = "" @decoyProteins = "" fork do @proteins = YAML.load_file(database) exit end fork do @decoyProteins = YAML.load_file(database) exit end p @proteins["LVDK"] P displays nil though because of the fork. So is it possible to have the forked processes share the variables? And if so, how?

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• How do I display a field's hidden characters in the result of a query in Oracle?

  - by Chris Williams

  I have two rows that have a varchar column that are different according to a Java .equals(). I can't easily change or debug the Java code that's running against this particular database but I do have access to do queries directly against the database using SQLDeveloper. The fields look the same to me (they are street addresses with two lines separated by some new line or carriage feed/new line combo). Is there a way to see all of the hidden characters as the result of a query?I'd like to avoid having to use the ascii() function with substr() on each of the rows to figure out which hidden character is different. I'd also accept some query that shows me which character is the first difference between the two fields.

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• Creating a triple store query using SQL - how to find all triples that have a common predicate and o

  - by Ankur

  I have a database that acts like a triple store, except that it is just a simple MySQL database. I want to select all triples that have a common predicate and object. Info about RDF and triples I can't seem to work out the SQL. If I had just a single predicate and object to match I would do: select TRIPLE from TRIPLES where PREDICATE="predicateName" and OBJECT="objectName" But if I have a list (HashMap) of many pairs of (predicateName,objectName) I am not sure what I need to do. Please let me know if I need to provide more info, I am not sure that I have made this quite clear, but I am wary of providing too much info and confusing the issue.

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• Catching constraint violations in JPA 2.0.

  - by Dennetik

  Consider the following entity class, used with, for example, EclipseLink 2.0.2 - where the link attribute is not the primary key, but unique nontheless. @Entity public class Profile { @Id private Long id; @Column(unique = true) private String link; // Some more attributes and getter and setter methods } When I insert records with a duplicate value for the link attribute, EclipseLink does not throw a EntityExistsException, but throws a DatabaseException, with the message explaining that the unique constraint was violated. This doesn't seem very usefull, as there would not be a simple, database independent, way to catch this exception. What would be the advised way to deal with this? A few things that I have considered are: Checking the error code on the DatabaseException - I fear that this error code, though, is the native error code for the database; Checking the existence of a Profile with the specific value for link beforehand - this obviously would result in an enormous amount of superfluous queries.

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• Problem with datagridvieew in vb.net

  - by user225269

  I'm trying to add a datagridview in vb.net, but it does not allow me to change the connection string or the database that should be imported to connect to it. The only thing that I'm seeing is the previous ms sql database that I connected with datagridview and everytime I click the new connection, the window closes and it leaves me with the datagridview with the previous connection that I have. And its not applicable because, now I want to connect it with mysql. Not ms sql. Its some sort of a cache like feature in vb.net, how do I get rid of it. so that I can add the new connection for mysql? Do I need to reinstall visual studio 2008?

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• Core Data: Overkill for simple, static UITableView-based iPhone App?

  - by David Foster

  Hello! I have a rather simple iPhone app consisting of numerous views containing a single, grouped table view. These views are held together in navigation controllers which are grouped in a tab bar. Simple stuff. My table views do little more than list text (like "Dog", "Cat" and "Weasel") and this data is being served from a collection of plists. It's perhaps worth mentioning too that these tables are 'static' in the sense that their data is pre-determined and will only ever be amended—and if so, very rarely indeed—by the developer (in this case, moi). This rudimentary approach has reached its limits though, and I think I'm going to need something a bit more relational. I have worked a tad with Core Data in the past, but only with apps whose data is determined by user input. I have four closely related questions: Is Core Data overkill for an app consisting mainly of a selection of simple table views? Do you recommend using Core Data to manage data which is predetermine and extremely unlikely to ever change? Can one lock Core Data down so that its data can't change, thereby relinquishing my responsibility as the developer to handle the editing and saving of the managed object context? How do I go about giving Core Data my predetermined data, and in a format I know that it can work with? Thanks a bunch guys.

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• Recommend me an architecture for this Facebook application

  - by andybaird

  Firstly, this question is subjective. There is not a right answer for this question and it really depends on what works for you. I'm hoping to use this thread as a breeding ground for ideas. I hope this is acceptable in this medium. I'm working on building a Facebook app that will be replacing an already popular app that gets ~50k hits a day. The original app is using a very typical LAMP setup with help from some Zend libraries for database layer extraction. For the most part the app worked well, except to solve a lot of issues I ended up fragmenting tables to speed things up. As a result, I couldn't do a lot of things with the app that I wanted to (namely any processing using aggregate data that needed to be returned quickly) So I'm starting to design plans for the next version of this application, and I have a whole bunch of new and cool features that I know would choke my current setup. I'm looking for technological recommendations of data storage methods that scale well. The database does not necessarily need to be relational, simple key/value storage would suffice (although at present time I know little to nothing about KV stores) What's your recommendation? How would you tackle this? I'd like to take a completely free approach to this -- although I am most familiar and comfortable using PHP, I want to leave all technical options open.

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• Concatenating databases with Squeryl

  - by Pengin

  I'm trying to use Squeryl to take the contents of a table from one database, and append it to the equivalent table in another database. The primary key will have to be reassigned in the process, but I'm getting the error NULL not allowed for column "SIMID". Why is this? object Concatenator { def main(args: Array[String]) { Class.forName("org.h2.Driver"); val seshA = Session.create( java.sql.DriverManager.getConnection("jdbc:h2:file:data/resultsA", "sa", "password"), new H2Adapter ) val seshB = Session.create( java.sql.DriverManager.getConnection("jdbc:h2:file:data/resultsB", "sa", "password"), new H2Adapter ) using(seshA){ import Library._ from(sims){s => select(s)}.foreach{item => using(seshB){ sims.insert(item); } } } } case class Simulation( @Column("SIMID") var id: Long, val date: Date ) extends KeyedEntity[Long] object Library extends Schema { val sims = table[Simulation] on(sims)(s => declare( s.id is(unique, indexed, autoIncremented) )) } }

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• Using a ICollection Value in sqlite SELECT parameterized statment

  - by case23

  Im trying to get all the entrys from a sqlite Database which have the same name as the keys in a Hashtable. My Statement looks like this. // the keys from the hashtable are names equivalent // to name entrys in the SomeTable Names Collumn Hashtable names; String query = "SELECT Id, Name FROM SomeTable WHERE Name LIKE (@Names)"; SQLiteCommand command = new SQLiteCommand(query, _databaseConnection); command.Parameters.AddWithValue("@Names", names.Keys); SQLiteDataReader reader = reader.ExecuteReader(); while(reader.Read()) { Console.WriteLine("Name: {0}, ID: {1}", reader[1].ToString(), reader[0].ToString()); } Im totally sure there are similar values in the Database, but i get nothing back and the reader does not execute. Is it impossible to add a ICollection as a Parameter Value so i need to start the reader only one time?

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• building a web application in eclipse

  - by Noona

  As a concluding assignment for the technologies taught in a data management course, we have to write a web application using the technologies taught throughout the course, this mostly includes xhtml, css, JSP, servelets, JDBC, AJAX, webservices. the project will eventually be deployed using tomcat. we are given the option of choosing the technologies that we see fit. since this is my first time developing a web application I am having some uncertainties about where to start, so for example now I am writing the object classes that will be used in the database and implementing the operations that will be performed on the database, but I am not sure about how to make these operations available to a client through the website, I mean I think I have to write a servlet through which I can extract the request parameters and set the response accordingly, but I would still like a more specific overview of what I am going to do, so if someone can link me to a tutorial with an example that makes use of these technologies while illustrating the stages of the design so that I can see how all these things are linked together in a web project. thanks

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• Does the Frontier Kernel have a future?

  - by pbreitenbach

  Whatever you think about Dave Winer, Frontier is an incredible piece of software. It includes quite a few advances that have yet to be surpassed: the object database, the database viewer, the scripting environment, the hierarchical-including website generation scheme, the elegant scripting language, the mixing of scripts and compilation, rapid prototyping, built in web server, simple debugger, cross-platform, simple UI, etc. My question: Dave turned Frontier over to open source and there is a Frontier Kernel project. However it is fairly quiet. Does Frontier have a future from here?

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• Iphone & Web App synch

  - by Jack Welsh

  I am trying to build an Iphone App client for our CRM solution so our sales people would be able to access the information available in our CRM through an Iphone App. I am trying to find out what is the recommended approach to architect the application when it comes to the database. I am not sure where should the data reside, should I save a subset of the data on the iPhone, or should I just rely on webservices and pull the information I need from the database whenever I need it. Also, is there any best practices or frameworks to build such applications on the Iphone.

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• Encoding issue with form and HTML Purifier / MySQL

  - by Andrew Heath

  Driving me nuts... Page with form is encoded as Unicode (UTF-8) via: <meta http-equiv="content-type" content="text/html; charset=utf-8"> entry column in database is text utf8_unicode_ci copying text from a Word document with " in it, like this: “1922.” is insta-fail and ends up in the database as â??1922.â?? (typing new data into the form, including " works fine... it's cut and pasting from Word...) PHP steps behind the scenes are: grab value from POST run through HTML Purifier default settings run through mysql_real_escape_string insert query into dbase Help?

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• Upgraded activerecord-sqlserver-adapter from 2.2.22 to 2.3.8 and now getting an ODBC error

  - by stuartc

  I have been using MSSQL 2005 with Rails for quite a while now, and decided to bump my gems up on one of my projects and ran into a problem. I moved from 2.2.22 to 2.3.8 (latest as of writing) and all of a sudden I got this: ODBC::Error: S1090 (0) [unixODBC][Driver Manager]Invalid string or buffer length I'm using a DSN connection with FreeTDS my database.yml looks like this: adapter: sqlserver mode: ODBC dsn: 'DRIVER=FreeTDS;TDSVER=7.0;SERVER=10.0.0.5;DATABASE=db;Port=1433;UID=user;PWD=pwd;' Now in the mean time I moved back to 2.2.22 and there are no deprecation warnings and everything seems fine but obviously for the sake of being up to date, any ideas what could have changed in the adaptor that could cause this?

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• SQL Server Import table keeping default values

  - by Chrissi

  I am importing a table from one database to another in SQL Server 2008 by right-clicking the target database and choosing Tasks Import Data... When I import the table I get the column names and types and all the data fine, but I lose the primary key, identity specifications and all the default values that were set in the source table. So now I have to set all the default values for each column again manually. Is there any way to get the default values with the import, or even after with a Query? I am VERY new to this and flailing in the dark, so forgive me if this is a really stupid question...

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• Losing DateTimeOffset precision when using C#

  - by Darvis Lombardo

  I have a SQL Server table with a CreatedDate field of type DateTimeOffset(2). A sample value which is in the table is 2010-03-01 15:18:58.57 -05:00 As an example, from within C# I retrieve this value like so: var cmd = new SqlCommand("SELECT CreatedDate FROM Entities WHERE EntityID = 2", cn); var da = new SqlDataAdapter(cmd); DataTable dt =new DataTable(); da.Fill(dt); And I look at the value: MessageBox.Show(dt.Rows[0][0].ToString()); The result is 2010-03-01 15:18:58 -05:00, which is missing the .57 that is stored in the database. If I look at dt.Rows[0][0] in the Watch window, I also do not see the .57, so it appears it has been truncated. Can someone shed some light on this? I need to use the date to match up with other records in the database and the .57 is needed. Thanks! Darvis

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• End User Ad-Hoc Reporting Tool: Microsoft SQL Server Management Studio or Microsoft Access?

  - by schultkl

  Our centralized IT department has suggested two primary ad hoc query tools for our general user base of approximately 200 staff members: Microsoft SQL Server Management Studio 2008 (SSMS) Microsoft Access 2003 Environment The backend database is a read-only Microsoft SQL Server 2005 database. The schema is 400+ tables; allowing access to the raw data for our general staff would be a disaster. We will be building an "abstraction layer" over the raw data for our general staff to run ad hoc queries against. The abstraction layer will most likely contain a number of views. A number of users have basic knowledge in Microsoft Access; none have used SSMS. Which of the above tools (or alternative) would be best for a decidedly non-techie user base of approximately 200 people? What are the pros and cons of each? Also, the IT department has suggested teaching people T-SQL so they may use SSMS. Is this reasonable?

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• asp.net webservice user management across pages

  - by nakori

  I'm developing a site that will display confidential readonly information, with data fetched from a WCF service. My question: What is the best approach to user management across different information pages. The service returns a collection with customer info after a secure login. My idea is to have a Customer object class that is stored in session. Is it possible to use things like HttpContext.Current.User.Identity.IsAuthenticated followed by HttpContext.Current.Session["UserId"] without using a database with role-based security? Would I be better off with a combination of local database, Linq to SQL or datasets rather than using just class objects for data fetched from service? thanks, nakori

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• Small methods - Small sprocs

  - by Berlioz

  Uncle Bob recommends having small methods. Do stored procedures have an ideal size? Or can they run on for 100's and 100's of lines long? Also does anyone have anything to say about where to place business logic. If located in stored procedures, the database is being used as data processing tier. If you read Adam Machanic, his bias is toward the database, does that imply long stored procedures that only the author of the sproc understands, leaving maintainers to deal with the mess? I guess there is two inter-related questions, somehow. Thanks in advance for responding to a fuzzy question(s).

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• Sparse (Pseudo) Infinite Grid Data Structure for Web Game

  - by Ming

  I'm considering trying to make a game that takes place on an essentially infinite grid. The grid is very sparse. Certain small regions of relatively high density. Relatively few isolated nonempty cells. The amount of the grid in use is too large to implement naively but probably smallish by "big data" standards (I'm not trying to map the Internet or anything like that) This needs to be easy to persist. Here are the operations I may want to perform (reasonably efficiently) on this grid: Ask for some small rectangular region of cells and all their contents (a player's current neighborhood) Set individual cells or blit small regions (the player is making a move) Ask for the rough shape or outline/silhouette of some larger rectangular regions (a world map or region preview) Find some regions with approximately a given density (player spawning location) Approximate shortest path through gaps of at most some small constant empty spaces per hop (it's OK to be a bad approximation often, but not OK to keep heading the wrong direction searching) Approximate convex hull for a region Here's the catch: I want to do this in a web app. That is, I would prefer to use existing data storage (perhaps in the form of a relational database) and relatively little external dependency (preferably avoiding the need for a persistent process). Guys, what advice can you give me on actually implementing this? How would you do this if the web-app restrictions weren't in place? How would you modify that if they were? Thanks a lot, everyone!

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• Problem with SQL syntax (probably simple)

  - by Bryan Folds

  I'm doing some custom database work for a module for Drupal and I get the following SQL error when trying to create my table: user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DEFAULT NULL, rooms INT DEFAULT NULL, adults INT DEFAULT NULL, children' at line 14 query: CREATE TABLE dr_enquiry ( eId INT unsigned NOT NULL auto_increment, eKey VARCHAR(16) NOT NULL, dateSent INT NOT NULL DEFAULT 0, status VARCHAR(30) NOT NULL DEFAULT 'Unanswered', custName VARCHAR(50) NOT NULL, custEmail VARCHAR(200) NOT NULL, custPhone VARCHAR(25) NOT NULL, custCountry VARCHAR(40) NOT NULL, custIP VARCHAR(11) DEFAULT NULL, offerName VARCHAR(100) NOT NULL, offerURL VARCHAR(200) NOT NULL, arrival DATETIME DEFAULT NULL, departure DEFAULT NULL, rooms INT DEFAULT NULL, adults INT DEFAULT NULL, children INT DEFAULT NULL, childAges VARCHAR(32) DEFAULT NULL, toddlers INT DEFAULT NULL, toddlerAges VARCHAR(32) DEFAULT NULL, catering VARCHAR(255) DEFAULT NULL, comments VARCHAR(255) DEFAULT NULL, agent VARCHAR(100) DEFAULT NULL, voucher VARCHAR(100) DEFAULT NULL, PRIMARY KEY (eId) ) /*!40100 DEFAULT CHARACTER SET UTF8 */ in /home/travelco/public_html/includes/database.inc on line 550.

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• How to order the items in a nested LINQ-provided collection

  - by Carson McComas

  I've got a (SQL Server) database table called Category. And another database table called SubCategory. SubCategory has a foreign key relationship to Category. Because of this, thanks to LINQ, each Cateogory has a property called SubCategories and LINQ is nice enough to return all the SubCategories associated with my Category when I grab it. If I want to sort the Categories alphabetically, I can just do: return db.Categories.OrderBy(c => c.Name); However, I have no idea how to order the SubCategories collection inside each Category. My goal is to return a collection of Categories, where all of the SubCategory collections inside of them are ordered alphabetically by Name.

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• .Remove(object) on a List<T> returned from LINQ to SQL compiled query won't delete the Object right

  - by soldieraman

  I am returning two lists from the database using LINQ to SQL compiled query. While looping the first list I remove duplicates from the second list as I dont want to process already existing objects again. eg. //oldCustomers is a List returned by my Compiled Linq to SQL Statmenet that I have added a .ToList() at the end to //Same goes for newCustomers for (Customer oC in oldCustomers) { //Do some processing newCustomers.Remove(newCusomters.Find(nC=> nC.CustomerID == oC.CusomterID)); } for (Cusomter nC in newCustomers) { //Do some processing } DataContext.SubmitChanges() I expect this to only save the changes that have been made to the customers in my processing and not Remove or Delete any of my customers from the database. Correct? I have tried it and it works fine - but I am trying to know if there is any rare case it might actually get removed

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• Howt o get the t-sql statements being used to Update a DataSet

  - by Dennis

  I've a c# DataSet object with one table in it, and put some data in it and i've made some changes to that dataset (by code). Is there a way to get the actual t-sql queries this dataset will perform on the sql server when I update the dataset to the database with code that looks something like this: var dataAdapter = new SqlDataAdapter(cmdText, connection); var affected = dataAdapter.Update(updatedDataSet); I want to know what queries this dataset will fire to the database so I can log these changes to a logfile in my c# program.

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