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• Complex SQL Query similar to a z order problem

  - by AaronLS

  I have a complex SQL problem in MS SQL Server, and in drawing on a piece of paper I realized that I could think of it as a single bar filled with rectangles, each rectangle having segments with different Z orders. In reality it has nothing to do with z order or graphics at all, but more to do with some complex business rules that would be difficult to explain. Howoever, if anyone has ideas on how to solve the below that will give me my solution. I have the following data: ObjectID, PercentOfBar, ZOrder (where smaller is closer) A, 100, 6 B, 50, 5 B, 50, 4 C, 30, 3 C, 70, 6 The result of my query that I want is this, in any order: PercentOfBar, ZOrder 50, 5 20, 4 30, 3 Think of it like this, if I drew rectangle A, it would fill 100% of the bar and have a z order of 6. 66666666666 AAAAAAAAAAA If I then layed out rectangle B, consisting of two segments, both segments would cover up rectangle A resulting in the following rendering: 4444455555 BBBBBBBBBB As a rule of thumb, for a given rectangle, it's segments should be layed out such that the highest z order is to the right of the lower Z orders. Finally rectangle C would cover up only portions of Rectangle B with it's 30% segment that is z order 3, which would be on the left. You can hopefully see how the is represented in the output dataset I listed above: 3334455555 CCCBBBBBBB Now to make things more complicated I actually have a 4th column such that this grouping occurs for each key: Input: SomeKey, ObjectID, PercentOfBar, ZOrder (where smaller is closer) X, A, 100, 6 X, B, 50, 5 X, B, 50, 4 X, C, 30, 3 X, C, 70, 6 Y, A, 100, 6 Z, B, 50, 2 Z, B, 50, 6 Z, C, 100, 5 Output: SomeKey, PercentOfBar, ZOrder X, 50, 5 X, 20, 4 X, 30, 3 Y, 100, 6 Z, 50, 2 Z, 50, 5 Notice in the output, the PercentOfBar for each SomeKey would add up to 100%. This is one I know I'm going to be thinking about when I go to bed tonight. Just to be explicit and have a question: What would be a query that would produce the results described above?

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• Atomic UPSERT in SQL Server 2005

  - by rabidpebble

  What is the correct pattern for doing an atomic "UPSERT" (UPDATE where exists, INSERT otherwise) in SQL Server 2005? I see a lot of code on SO (e.g. see http://stackoverflow.com/questions/639854/tsql-check-if-a-row-exists-otherwise-insert) with the following two-part pattern: UPDATE ... FROM ... WHERE <condition> -- race condition risk here IF @@ROWCOUNT = 0 INSERT ... or IF (SELECT COUNT(*) FROM ... WHERE <condition>) = 0 -- race condition risk here INSERT ... ELSE UPDATE ... where will be an evaluation of natural keys. None of the above approaches seem to deal well with concurrency. If I cannot have two rows with the same natural key, it seems like all of the above risk inserting rows with the same natural keys in race condition scenarios. I have been using the following approach but I'm surprised not to see it anywhere in people's responses so I'm wondering what is wrong with it: INSERT INTO <table> SELECT <natural keys>, <other stuff...> FROM <table> WHERE NOT EXISTS -- race condition risk here? ( SELECT 1 FROM <table> WHERE <natural keys> ) UPDATE ... WHERE <natural keys> (Note: I'm assuming that rows will not be deleted from this table. Although it would be nice to discuss how to handle the case where they can be deleted -- are transactions the only option? Which level of isolation?) Is this atomic? I can't locate where this would be documented in SQL Server documentation.

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• Can I select 0 columns in SQL Server?

  - by Woody Zenfell III

  I am hoping this question fares a little better than the similar Create a table without columns. Yes, I am asking about something that will strike most as pointlessly academic. It is easy to produce a SELECT result with 0 rows (but with columns), e.g. SELECT a = 1 WHERE 1 = 0. Is it possible to produce a SELECT result with 0 columns (but with rows)? e.g. something like SELECT NO COLUMNS FROM Foo. (This is not valid T-SQL.) I came across this because I wanted to insert several rows without specifying any column data for any of them. e.g. (SQL Server 2005) CREATE TABLE Bar (id INT NOT NULL IDENTITY PRIMARY KEY) INSERT INTO Bar SELECT NO COLUMNS FROM Foo -- Invalid column name 'NO'. -- An explicit value for the identity column in table 'Bar' can only be specified when a column list is used and IDENTITY_INSERT is ON. One can insert a single row without specifying any column data, e.g. INSERT INTO Foo DEFAULT VALUES. One can query for a count of rows (without retrieving actual column data from the table), e.g. SELECT COUNT(*) FROM Foo. (But that result set, of course, has a column.) I tried things like INSERT INTO Bar () SELECT * FROM Foo -- Parameters supplied for object 'Bar' which is not a function. -- If the parameters are intended as a table hint, a WITH keyword is required. and INSERT INTO Bar DEFAULT VALUES SELECT * FROM Foo -- which is a standalone INSERT statement followed by a standalone SELECT statement. I can do what I need to do a different way, but the apparent lack of consistency in support for degenerate cases surprises me. I read through the relevant sections of BOL and didn't see anything. I was surprised to come up with nothing via Google either.

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• How to Convert using of SqlLit to Simple SQL command in C#

  - by Nasser Hajloo

  I want to get start with DayPilot control I do not use SQLLite and this control documented based on SQLLite. I want to use SQL instead of SQL Lite so if you can, please do this for me. main site with samples http://www.daypilot.org/calendar-tutorial.html The database contains a single table with the following structure CREATE TABLE event ( id VARCHAR(50), name VARCHAR(50), eventstart DATETIME, eventend DATETIME); Loading Events private DataTable dbGetEvents(DateTime start, int days) { SQLiteDataAdapter da = new SQLiteDataAdapter("SELECT [id], [name], [eventstart], [eventend] FROM [event] WHERE NOT (([eventend] <= @start) OR ([eventstart] >= @end))", ConfigurationManager.ConnectionStrings["db"].ConnectionString); da.SelectCommand.Parameters.AddWithValue("start", start); da.SelectCommand.Parameters.AddWithValue("end", start.AddDays(days)); DataTable dt = new DataTable(); da.Fill(dt); return dt; } Update private void dbUpdateEvent(string id, DateTime start, DateTime end) { using (SQLiteConnection con = new SQLiteConnection(ConfigurationManager.ConnectionStrings["db"].ConnectionString)) { con.Open(); SQLiteCommand cmd = new SQLiteCommand("UPDATE [event] SET [eventstart] = @start, [eventend] = @end WHERE [id] = @id", con); cmd.Parameters.AddWithValue("id", id); cmd.Parameters.AddWithValue("start", start); cmd.Parameters.AddWithValue("end", end); cmd.ExecuteNonQuery(); } }

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• Linq to SQL not inserting data onto the DB

  - by Jesus Rodriguez

  Hello! I have a little / weird behaviour here and Im looking over internet and SO and I didn't find a response. I have to admit that this is my first time using databases, I know how to use them with SQL but never used it actually. Anyway, I have a problem with my app inserting data, I just created a very simple project for testing that and no solution yet. I have an example database with Sql Server Id - int (identity primary key) Name - nchar(10) (not null) The table is called "Person", simple as pie. I have this: static void Main(string[] args) { var db = new ExampleDBDataContext {Log = Console.Out}; var jesus = new Person {Name = "Jesus"}; db.Persons.InsertOnSubmit(jesus); db.SubmitChanges(); var query = from person in db.Persons select person; foreach (var p in query) { Console.WriteLine(p.Name); } } As you can see, nothing extrange. It show Jesus in the console. But if you see the table data, there is no data, just empty. I comment the object creation and insertion and the foreach doesn't print a thing (normal, there is no data in the database) The weird thing is that I created a row in the database manually and the Id was 2 and no 1 (Was the linq really playing with the database but it didn't create the row?) There is the log: INSERT INTO [dbo].Person VALUES (@p0) SELECT CONVERT(Int,SCOPE_IDENTITY()) AS [value] -- @p0: Input NChar (Size = 10; Prec = 0; Scale = 0) [Jesus] -- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.30729.4926 SELECT [t0].[Id], [t0].[Name] FROM [dbo].[Person] AS [t0] -- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.30729.4926 I am really confused, All the blogs / books use this kind of snippet to insert an element to a database. Thank you for helping.

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• What does SQL Server's BACKUPIO wait type mean?

  - by solublefish

  I'm using Sql Server 2008 ("R1"), with some maintenance plans that back up my databases to a network share. Some of my backup jobs show long waits of type "BACKUPIO". Of course it seems like this is an I/O subsystem limitation, but I'm skeptical. Perfmon stats for I/O on the production (source) server are well within normal trends for that server. The destination server shows a sustained 7MB/s write rate, which seems incredibly low, even for a slow disk. The network link is gigabit ethernet and nowhere near saturated. The few docs I've turned up about BACKUPIO indicate that it's not specifically a wait on I/O, surprisingly enough. This MSFT doc says it's abnormal unless you're using a tape drive, which I'm not. But it doesn't say (or I don't understand) exactly what resource is missing. http://www.docstoc.com/docs/24580659/Performance-Tuning-in-SQL-Server-2005 And this piece says it's not related to I/O performance at all. http://www.informit.com/articles/article.aspx?p=686168&seqNum=5 "Note that BACKUPIO and IO_AUDIT_MUTEX are not related to IO performance." Anyway, does anyone know what BACKUPIO actually means and/or what I can do to diagnose or eliminate it?

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• SQL Server 2005 Reporting Services and the Report Viewer

  - by Kendra

  I am having an issue embedding my report into an aspx page. Here's my setup: 1 Server running SQL Server 2005 and SQL Server 2005 Reporting Services 1 Workstation running XP and VS 2005 The server is not on a domain. Reporting Services is a default installation. I have one report called TestMe in a folder called TestReports using a shared datasource. If I view the report in Report Manager, it renders fine. If I view the report using the http ://myserver/reportserver url it renders fine. If I view the report using the http ://myserver/reportserver?/TestReports/TestMe it renders fine. If I try to view the report using http ://myserver/reportserver/TestReports/TestMe, it just goes to the folder navigation page of the home directory. My web application is impersonating somebody specific to get around the server not being on a domain. When I call the report from the report viewer using http ://myserver/reportserver as the server and /TestReports/TestMe as the path I get this error: For security reasons DTD is prohibited in this XML document. To enable DTD processing set the ProhibitDtd property on XmlReaderSettings to false and pass the settings into XmlReader.Create method. When I change the server to http ://myserver/reportserver? I get this error when I run the report: Client found response content type of '', but expected 'text/xml'. The request failed with an empty response. I have been searching for a while and haven't found anything that fixes my issue. Please let me know if there is more information needed. Thanks in advance, Kendra

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• SQL Query slow in .NET application but instantaneous in SQL Server Management Studio

  - by user203882

  Here is the SQL SELECT tal.TrustAccountValue FROM TrustAccountLog AS tal INNER JOIN TrustAccount ta ON ta.TrustAccountID = tal.TrustAccountID INNER JOIN Users usr ON usr.UserID = ta.UserID WHERE usr.UserID = 70402 AND ta.TrustAccountID = 117249 AND tal.trustaccountlogid = ( SELECT MAX (tal.trustaccountlogid) FROM TrustAccountLog AS tal INNER JOIN TrustAccount ta ON ta.TrustAccountID = tal.TrustAccountID INNER JOIN Users usr ON usr.UserID = ta.UserID WHERE usr.UserID = 70402 AND ta.TrustAccountID = 117249 AND tal.TrustAccountLogDate < '3/1/2010 12:00:00 AM' ) Basicaly there is a Users table a TrustAccount table and a TrustAccountLog table. Users: Contains users and their details TrustAccount: A User can have multiple TrustAccounts. TrustAccountLog: Contains an audit of all TrustAccount "movements". A TrustAccount is associated with multiple TrustAccountLog entries. Now this query executes in milliseconds inside SQL Server Management Studio, but for some strange reason it takes forever in my C# app and even timesout (120s) sometimes. Here is the code in a nutshell. It gets called multiple times in a loop and the statement gets prepared. cmd.CommandTimeout = Configuration.DBTimeout; cmd.CommandText = "SELECT tal.TrustAccountValue FROM TrustAccountLog AS tal INNER JOIN TrustAccount ta ON ta.TrustAccountID = tal.TrustAccountID INNER JOIN Users usr ON usr.UserID = ta.UserID WHERE usr.UserID = @UserID1 AND ta.TrustAccountID = @TrustAccountID1 AND tal.trustaccountlogid = (SELECT MAX (tal.trustaccountlogid) FROM TrustAccountLog AS tal INNER JOIN TrustAccount ta ON ta.TrustAccountID = tal.TrustAccountID INNER JOIN Users usr ON usr.UserID = ta.UserID WHERE usr.UserID = @UserID2 AND ta.TrustAccountID = @TrustAccountID2 AND tal.TrustAccountLogDate < @TrustAccountLogDate2 ))"; cmd.Parameters.Add("@TrustAccountID1", SqlDbType.Int).Value = trustAccountId; cmd.Parameters.Add("@UserID1", SqlDbType.Int).Value = userId; cmd.Parameters.Add("@TrustAccountID2", SqlDbType.Int).Value = trustAccountId; cmd.Parameters.Add("@UserID2", SqlDbType.Int).Value = userId; cmd.Parameters.Add("@TrustAccountLogDate2", SqlDbType.DateTime).Value =TrustAccountLogDate; // And then... reader = cmd.ExecuteReader(); if (reader.Read()) { double value = (double)reader.GetValue(0); if (System.Double.IsNaN(value)) return 0; else return value; } else return 0;

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• SQL Server 2005 standard filegroups / files for performance on SAN

  - by Blootac

  Ok so I've just been on a SQL Server course and we discussed the usage scenarios of multiple filegroups and files when in use over local RAID and local disks but we didn't touch SAN scenarios so my question is as follows; I currently have a 250 gig database running on SQL Server 2005 where some tables have a huge number of writes and others are fairly static. The database and all objects reside in a single file group with a single data file. The log file is also on the same volume. My interpretation is that separate data files should be used across different disks to lessen disk contention and that file groups should be used for partitioning of data. However, with a SAN you obviously don't really have the same issue of disk contention that you do with a small RAID setup (or at least we don't at the moment), and standard edition doesn't support partitioning. So in order to improve parallelism what should I do? My understanding of various Microsoft publications is that if I increase the number of data files, separate threads can act across each file separately. Which leads me to the question how many files should I have. One per core? Should I be putting tables and indexes with high levels of activity in separate file groups, each with the same number of data files as we have cores? Thank you

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• SQL Where Clause Against View

  - by Adam Carr

  I have a view (actually, it's a table valued function, but the observed behavior is the same in both) that inner joins and left outer joins several other tables. When I query this view with a where clause similar to SELECT * FROM [v_MyView] WHERE [Name] like '%Doe, John%' ... the query is very slow, but if I do the following... SELECT * FROM [v_MyView] WHERE [ID] in ( SELECT [ID] FROM [v_MyView] WHERE [Name] like '%Doe, John%' ) it is MUCH faster. The first query is taking at least 2 minutes to return, if not longer where the second query will return in less than 5 seconds. Any suggestions on how I can improve this? If I run the whole command as one SQL statement (without the use of a view) it is very fast as well. I believe this result is because of how a view should behave as a table in that if a view has OUTER JOINS, GROUP BYS or TOP ##, if the where clause was interpreted prior to vs after the execution of the view, the results could differ. My question is why wouldn't SQL optimize my first query to something as efficient as my second query?

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• SQL Server Clustered Index: (Physical) Data Page Order

  - by scherand

  I am struggling understanding what a clustered index in SQL Server 2005 is. I read the MSDN article Clustered Index Structures (among other things) but I am still unsure if I understand it correctly. The (main) question is: what happens if I insert a row (with a "low" key) into a table with a clustered index? The above mentioned MSDN article states: The pages in the data chain and the rows in them are ordered on the value of the clustered index key. And Using Clustered Indexes for example states: For example, if a record is added to the table that is close to the beginning of the sequentially ordered list, any records in the table after that record will need to shift to allow the record to be inserted. Does this mean that if I insert a row with a very "low" key into a table that already contains a gazillion rows literally all rows are physically shifted on disk? I cannot believe that. This would take ages, no? Or is it rather (as I suspect) that there are two scenarios depending on how "full" the first data page is. A) If the page has enough free space to accommodate the record it is placed into the existing data page and data might be (physically) reordered within that page. B) If the page does not have enough free space for the record a new data page would be created (anywhere on the disk!) and "linked" to the front of the leaf level of the B-Tree? This would then mean the "physical order" of the data is restricted to the "page level" (i.e. within a data page) but not to the pages residing on consecutive blocks on the physical hard drive. The data pages are then just linked together in the correct order. Or formulated in an alternative way: if SQL Server needs to read the first N rows of a table that has a clustered index it can read data pages sequentially (following the links) but these pages are not (necessarily) block wise in sequence on disk (so the disk head has to move "randomly"). How close am I? :)

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• sp_addlinkedserver on sql server 2005 giving problem

  - by Jit

  I am trying to create a link server of a remote database(both the servers are SQL serve2005). I am able to connect that remote server from my SQL Server management studio. I used the following syntax to create it. EXEC sp_addlinkedserver @server = N'LINKSQL2005', @srvproduct = N'', @provider = N'SQLNCLI', @provstr = N'SERVER=IP Address of remote server ;User ID=XXXXXX;Password=***' I have provided the IP addressntax. and user name and password in the above syntax. The link server is getting created. But when I try to execute a query on it I get the error below. Query Used. select * from LINKSQL2005.<DBName>.dbo.<TableName> OLE DB provider "SQLNCLI" for linked server "LINKSQL2005" returned message "Communication link failure". Msg 10054, Level 16, State 1, Line 0 TCP Provider: An existing connection was forcibly closed by the remote host. Msg 18456, Level 14, State 1, Line 0 Login failed for user 'sa'. OLE DB provider "SQLNCLI" for linked server "LINKSQL2005" returned message "Invalid connection string attribute". Pls help me, where am I making mistake.

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• SQL Server database change workflow best practices

  - by kubi

  The Background My group has 4 SQL Server Databases: Production UAT Test Dev I work in the Dev environment. When the time comes to promote the objects I've been working on (tables, views, functions, stored procs) I make a request of my manager, who promotes to Test. After testing, she submits a request to an Admin who promotes to UAT. After successful user testing, the same Admin promotes to Production. The Problem The entire process is awkward for a few reasons. Each person must manually track their changes. If I update, add, remove any objects I need to track them so that my promotion request contains everything I've done. In theory, if I miss something testing or UAT should catch it, but this isn't certain and it's a waste of the tester's time, anyway. Lots of changes I make are iterative and done in a GUI, which means there's no record of what changes I made, only the end result (at least as far as I know). We're in the fairly early stages of building out a data mart, so the majority of the changes made, at least count-wise, are minor things: changing the data type for a column, altering the names of tables as we crystallize what they'll be used for, tweaking functions and stored procs, etc. The Question People have been doing this kind of work for decades, so I imagine there have got to be a much better way to manage the process. What I would love is if I could run a diff between two databases to see how the structure was different, use that diff to generate a change script, use that change script as my promotion request. Is this possible? If not, are there any other ways to organize this process? For the record, we're a 100% Microsoft shop, just now updating everything to SQL Server 2008, so any tools available in that package would be fair game.

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• General SQL Server query performance

  - by Kiril

  Hey guys, This might be stupid, but databases are not my thing :) Imagine the following scenario. A user can create a post and other users can reply to his post, thus forming a thread. Everything goes in a single table called Posts. All the posts that form a thread are connected with each other through a generated key called ThreadID. This means that when user #1 creates a new post, a ThreadID is generated, and every reply that follows has a ThreadID pointing to the initial post (created by user #1). What I am trying to do is limit the number of replies to let's say 20 per thread. I'm wondering which of the approaches bellow is faster: 1 I add a new integer column (e.x. Counter) to Posts. After a user replies to the initial post, I update the initial post's Counter field. If it reaches 20 I lock the thread. 2 After a user replies to the initial post, I select all the posts that have the same ThreadID. If this collection has more than 20 items, I lock the thread. For further information: I am using SQL Server database and Linq-to-SQL entity model. I'd be glad if you tell me your opinions on the two approaches or share another, faster approach. Best Regards, Kiril

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• "Order By" in LINQ-to-SQL Causes performance issues

  - by panamack

  I've set out to write a method in my C# application which can return an ordered subset of names from a table containing about 2000 names starting at the 100th name and returning the next 20 names. I'm doing this so I can populate a WPF DataGrid in my UI and do some custom paging. I've been using LINQ to SQL but hit a snag with this long executing query so I'm examining the SQL the LINQ query is using (Query B below). Query A runs well: SELECT TOP (20) [t0].[subject_id] AS [Subject_id], [t0].[session_id] AS [Session_id], [t0].[name] AS [Name] FROM [Subjects] AS [t0] WHERE (NOT (EXISTS( SELECT NULL AS [EMPTY] FROM ( SELECT TOP (100) [t1].[subject_id] FROM [Subjects] AS [t1] WHERE [t1].[session_id] = 1 ORDER BY [t1].[name] ) AS [t2] WHERE [t0].[subject_id] = [t2].[subject_id] ))) AND ([t0].[session_id] = 1) Query B takes 40 seconds: SELECT TOP (20) [t0].[subject_id] AS [Subject_id], [t0].[session_id] AS [Session_id], [t0].[name] AS [Name] FROM [Subjects] AS [t0] WHERE (NOT (EXISTS( SELECT NULL AS [EMPTY] FROM ( SELECT TOP (100) [t1].[subject_id] FROM [Subjects] AS [t1] WHERE [t1].[session_id] = 1 ORDER BY [t1].[name] ) AS [t2] WHERE [t0].[subject_id] = [t2].[subject_id] ))) AND ([t0].[session_id] = 1) ORDER BY [t0].[name] When I add the ORDER BY [t0].[name] to the outer query it slows down the query. How can I improve the second query? This was my LINQ stuff Nick int sessionId = 1; int start = 100; int count = 20; // Query subjects with the shoot's session id var subjects = cldb.Subjects.Where<Subject>(s => s.Session_id == sessionId); // Filter as per params var orderedSubjects = subjects .OrderBy<Subject, string>( s => s.Col_zero ); var filteredSubjects = orderedSubjects .Skip<Subject>(start) .Take<Subject>(count);

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• Using SQL dB column as a lock for concurrent operations in Entity Framework

  - by Sid

  We have a long running user operation that is handled by a pool of worker processes. Data input and output is from Azure SQL. The master Azure SQL table structure columns are approximated to [UserId, col1, col2, ... , col N, beingProcessed, lastTimeProcessed ] beingProcessed is boolean and lastTimeProcessed is DateTime. The logic in every worker role is: public void WorkerRoleMain() { while(true) { try { dbContext db = new dbContext(); // Read foreach (UserProfile user in db.UserProfile .Where(u => DateTime.UtcNow.Subtract(u.lastTimeProcessed) > TimeSpan.FromHours(24) & u.beingProcessed == false)) { user.beingProcessed = true; // Modify db.SaveChanges(); // Write // Do some long drawn processing here ... ... ... user.lastTimeProcessed = DateTime.UtcNow; user.beingProcessed = false; db.SaveChanges(); } } catch(Exception ex) { LogException(ex); Sleep(TimeSpan.FromMinutes(5)); } } // while () } With multiple workers processing as above (each with their own Entity Framework layer), in essence beingProcessed is being used a lock for MutEx purposes Question: How can I deal with concurrency issues on the beingProcessed "lock" itself based on the above load? I think read-modify-write operation on the beingProcessed needs to be atomic but I'm open to other strategies. Open to other code refinements too.

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• Group / User based security. Table / SQL question

  - by Brett

  Hi, I'm setting up a group / user based security system. I have 4 tables as follows: user groups group_user_mappings acl where acl is the mapping between an item_id and either a group or a user. The way I've done the acl table, I have 3 columns of note (actually 4th one as an auto-id, but that is irrelevant) col 1 item_id (item to access) col 3 user_id (user that is allowed to access) col 3 group_id (group that is allowed to access) So for example item1, peter, , item2, , group1 item3, jane, , so either the acl will give access to a user or a group. Any one line in the ACL table with either have an item - user mapping, or an item group. If I want to have a query that returns all objects a user has access to, I think I need to have a SQL query with a UNION, because I need 2 separate queries that join like.. item - acl - group - user AND item - acl - user This I guess will work OK. Is this how its normally done? Am I doing this the right way? Seems a little messy. I was thinking I could get around it by creating a single user group for each person, so I only ever deal with groups in my SQL, but this seems a little messy as well..

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• SQL Server: preventing dirty reads in a stored procedure

  - by pcampbell

  Consider a SQL Server database and its two stored procs: *1. A proc that performs 3 important things in a transaction: Create a customer, call a sproc to perform another insert, and conditionally insert a third record with the new identity. BEGIN TRAN INSERT INTO Customer(CustName) (@CustomerName) SELECT @NewID = SCOPE_IDENTITY() EXEC CreateNewCustomerAccount @NewID, @CustomerPhoneNumber IF @InvoiceTotal > 100000 INSERT INTO PreferredCust(InvoiceTotal, CustID) VALUES (@InvoiceTotal, @NewID) COMMIT TRAN *2. A stored proc which polls the Customer table for new entries that don't have a related PreferredCust entry. The client app performs the polling by calling this stored proc every 500ms. A problem has arisen where the polling stored procedure has found an entry in the Customer table, and returned it as part of its results. The problem was that it has picked up that record, I am assuming, as part of a dirty read. The record ended up having an entry in PreferredCust later, and ended up creating a problem downstream. Question How can you explicitly prevent dirty reads by that second stored proc? The environment is SQL Server 2005 with the default configuration out of the box. No other locking hits are given in either of these stored procedures.

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• Update or Insert Row depending on whether row is present in Microsoft SQL Server 2005

  - by Srikanth

  Hi, I am passing a XML document as a input to a stored procedure in Microsoft SQL Server 2005. This is the sample XML being passed as input <Strategy StrategyID="0" TOStrategyID="8" ShutdownQtySell="1" ShutdownQtyBuy="1"> <ParameterRange ParameterSetID="6" ParameterRangeID="1" ParameterRangeFrom="0" ParameterRangeTo="20" ParameterAutoTakeOut="False"> </ParameterRange> <ParameterRange ParameterSetID="6" ParameterRangeID="4" ParameterRangeFrom="21" ParameterRangeTo="40" ParameterAutoTakeOut="False"> </ParameterRange> <ParameterRange ParameterSetID="6" ParameterRangeID="5" ParameterRangeFrom="41" ParameterRangeTo="60" ParameterAutoTakeOut="False"> </ParameterRange> <ParameterRange ParameterSetID="6" ParameterRangeID="6" ParameterRangeFrom="61" ParameterRangeTo="80" ParameterAutoTakeOut="False"> </ParameterRange> <ParameterRange ParameterSetID="6" ParameterRangeID="7" ParameterRangeFrom="81" ParameterRangeTo="100" ParameterAutoTakeOut="False"> </ParameterRange> </Strategy> I am able to retrieve the data using OpenXML functionality in SQL server I am using this to get the data corresponding to ParameterRange rows SELECT ParameterRangeID as iRangeID, ParameterSetID as iSetID, ParameterRangeFrom as fRangeFrom, ParameterRangeTo as fRangeTo, ParameterAutoTakeOut as bTakeoutEnabled FROM OPENXML(@idoc, '/Strategy/ParameterRange', 1) WITH (ParameterSetID int,ParameterRangeID int,ParameterRangeFrom float,ParameterRangeTo float,ParameterAutoTakeOut bit) Now, I need to insert/update these rows into a table TempRanges which has (iRangeID,iSetID) as the primary key. If there is a row with the primary key, I want to update it the latest values and If there is no row with that primary key, I need to insert into the table. How can I accomplish this inside the Stored Procedure ? Thanks, Sri

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• Database table relationships: Always also relate to specified value (Linq to SQL in .NET Framework)

  - by sinni800

  I really can not describe my question better in the title. If anyone has suggestions: Please tell! I use the Linq to SQL framework in .NET. I ran into something which could be easily solved if the framework supported this, it would be a lot of extra coding otherwise: I have a n to n relation with a helper table in between. Those tables are: Items, places and the connection table which relates items to places and the other way. One item can be found in many places, so can one place have many items. Now of course there will be many items which will be in ALL places. Now there is a problem: Places can always be added. So I need a place-ID which encompasses ALL places, always. Like maybe a place-id "0". If the helper table has a row with the place-id of zero, this should be visible in all places. In SQL this would be a simple "Where [...] or place-id = 0", but how do I do this in Linq relations? Also, for a little side question: How could I manage "all but this place" kind of exclusions?

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• 'LINQ query plan' horribly inefficient but 'Query Analyser query plan' is perfect for same SQL!

  - by Simon_Weaver

  I have a LINQ to SQL query that generates the following SQL : exec sp_executesql N'SELECT COUNT(*) AS [value] FROM [dbo].[SessionVisit] AS [t0] WHERE ([t0].[VisitedStore] = @p0) AND (NOT ([t0].[Bot] = 1)) AND ([t0].[SessionDate] > @p1)',N'@p0 int,@p1 datetime', @p0=1,@p1='2010-02-15 01:24:00' (This is the actual SQL taken from SQL Profiler on SQL Server 2008.) The query plan generated when I run this SQL from within Query Analyser is perfect. It uses an index containing VisitedStore, Bot, SessionDate. The query returns instantly. However when I run this from C# (with LINQ) a different query plan is used that is so inefficient it doesn't even return in 60 seconds. This query plan is trying to do a key lookup on the clustered primary key which contains a couple million rows. It has no chance of returning. What I just can't understand though is that the EXACT same SQL is being run - either from within LINQ or from within Query Analyser yet the query plan is different. I've ran the two queries many many times and they're now running in isolation from any other queries. The date is DateTime.Now.AddDays(-7), but I've even hardcoded that date to eliminate caching problems. Is there anything i can change in LINQ to SQL to affect the query plan or try to debug this further? I'm very very confused!

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• SQL: select rows with the same order as IN clause

  - by Andrea3000

  I know that this question has been asked several times and I've read all the answer but none of them seem to completely solve my problem. I'm switching from a mySQL database to a MS Access database with MS SQL. In both of the case I use a php script to connect to the database and perform SQL queries. I need to find a suitable replacement for a query I used to perform on mySQL. I want to: perform a first query and order records alphabetically based on one of the columns construct a list of IDs which reflects the previous alphabetical order perform a second query with the IN clause applied with the IDs' list and ordered by this list. In mySQL I used to perform the last query this way: SELECT name FROM users WHERE id IN ($name_ids) ORDER BY FIND_IN_SET(id,'$name_ids') Since FIND_IN_SET is available only in mySQL and CHARINDEX and PATINDEX are not available from my php script, how can I achieve this? I know that I could write something like: SELECT name FROM users WHERE id IN ($name_ids) ORDER BY CASE id WHEN ... THEN 1 WHEN ... THEN 2 WHEN ... THEN 3 WHEN ... THEN 4 END but you have to consider that: IDs' list has variable length and elements because it depends on the first query that list can easily contains thousands of elements Have you got any hint on this? Is there a way to programmatically construct the ORDER BY CASE ... WHEN ... statement? Is there a better approach since my list of IDs can be big?

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• Generated sql from LINQ to SQL

  - by Muhammad Kashif Nadeem

  Following code ProductPricesDataContext db = new ProductPricesDataContext(); var products = from p in db.Products where p.ProductFields.Count > 3 select new { ProductIDD = p.ProductId, ProductName = p.ProductName.Contains("hotel"), NumbeOfProd = p.ProductFields.Count, totalFields = p.ProductFields.Sum(o => o.FieldId + o.FieldId) }; Generated follwing sql SELECT [t0].[ProductId] AS [ProductIDD], (CASE WHEN [t0].[ProductName] LIKE '%hotel%' THEN 1 WHEN NOT ([t0].[ProductName] LIKE '%hotel%') THEN 0 ELSE NULL END) AS [ProductName], ( SELECT COUNT(*) FROM [dbo].[ProductField] AS [t2] WHERE [t2].[ProductId] = [t0].[ProductId] ) AS [NumbeOfProd], ( SELECT SUM([t3].[FieldId] + [t3].[FieldId]) FROM [dbo].[ProductField] AS [t3] WHERE [t3].[ProductId] = [t0].[ProductId]) AS [totalFields] FROM [dbo].[Product] AS [t0] WHERE (( SELECT COUNT(*) FROM [dbo].[ProductField] AS [t1] WHERE [t1].[ProductId] = [t0].[ProductId] )) > 3 Why is this CASE statement for ProductName and because of this instead of ProductName i am just getting 0 in my result set. It should generate sql like following, (where ProductName like '%hotel%' SELECT [t0].[ProductId] AS [ProductIDD], [ProductName], ( SELECT COUNT(*) FROM [dbo].[ProductField] AS [t2] WHERE [t2].[ProductId] = [t0].[ProductId] ) AS [NumbeOfProd], ( SELECT SUM([t3].[FieldId] + [t3].[FieldId]) FROM [dbo].[ProductField] AS [t3] WHERE [t3].[ProductId] = [t0].[ProductId]) AS [totalFields] FROM [dbo].[Product] AS [t0] WHERE (( SELECT COUNT(*) FROM [dbo].[ProductField] AS [t1] WHERE [t1].[ProductId] = [t0].[ProductId] )) > 3 AND t0.ProductName like '%hotel%' Thanks.

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• Interesting LinqToSql behaviour

  - by Ben Robinson

  We have a database table that stores the location of some wave files plus related meta data. There is a foreign key (employeeid) on the table that links to an employee table. However not all wav files relate to an employee, for these records employeeid is null. We are using LinqToSQl to access the database, the query to pull out all non employee related wav file records is as follows: var results = from Wavs in db.WaveFiles where Wavs.employeeid == null; Except this returns no records, despite the fact that there are records where employeeid is null. On profiling sql server i discovered the reason no records are returned is because LinqToSQl is turning it into SQL that looks very much like: SELECT Field1, Field2 //etc FROM WaveFiles WHERE 1=0 Obviously this returns no rows. However if I go into the DBML designer and remove the association and save. All of a sudden the exact same LINQ query turns into SELECT Field1, Field2 //etc FROM WaveFiles WHERE EmployeeID IS NULL I.e. if there is an association then LinqToSql assumes that all records have a value for the foreign key (even though it is nullable and the property appears as a nullable int on the WaveFile entity) and as such deliverately constructs a where clause that will return no records. Does anyone know if there is a way to keep the association in LinqToSQL but stop this behaviour. A workaround i can think of quickly is to have a calculated field called IsSystemFile and set it to 1 if employeeid is null and 0 otherwise. However this seems like a bit of a hack to work around strange behaviour of LinqToSQl and i would rather do something in the DBML file or define something on the foreign key constraint that will prevent this behaviour.

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• PHP -- automatic SQL injection protection?

  - by ashgromnies

  I took over maintenance of a PHP app recently and I'm not super familiar with PHP but some of the things I've been seeing on the site are making me nervous that it could be vulnerable to a SQL injection attack. For example, see how this code for logging into the administrative section works: $password = md5(HASH_SALT . $_POST['loginPass']); $query = "SELECT * FROM `administrators` WHERE `active`='1' AND `email`='{$_POST['loginEmail']}' AND `password`='{$password}'"; $userInfo = db_fetch_array(db_query($query)); if($userInfo['id']) { $_SESSION['adminLoggedIn'] = true; // user is logged in, other junk happens here, not important The creators of the site made a special db_query method and db_fetch_array method, shown here: function db_query($qstring,$print=0) { return @mysql(DB_NAME,$qstring); } function db_fetch_array($qhandle) { return @mysql_fetch_array($qhandle); } Now, this makes me think I should be able to do some sort of SQL injection attack with an email address like: ' OR 'x'='x' LIMIT 1; and some random password. When I use that on the command line, I get an administrative user back, but when I try it in the application, I get an invalid username/password error, like I should. Could there be some sort of global PHP configuration they have enabled to block these attacks? Where would that be configured? Here is the PHP --version information: # php --version PHP 5.2.12 (cli) (built: Feb 28 2010 15:59:21) Copyright (c) 1997-2009 The PHP Group Zend Engine v2.2.0, Copyright (c) 1998-2009 Zend Technologies with the ionCube PHP Loader v3.3.14, Copyright (c) 2002-2010, by ionCube Ltd., and with Zend Optimizer v3.3.9, Copyright (c) 1998-2009, by Zend Technologies

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