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• Linq to SQL DynamicInvoke(System.Object[])' has no supported translation to SQL.

  - by ewwwyn

  I have a class, Users. Users has a UserId property. I have a method that looks something like this: static IQueryable<User> FilterById(this IQueryable<User> p, Func<int, bool> sel) { return p.Where(m => sel(m)); } Inevitably, when I call the function: var users = Users.FilterById(m => m > 10); I get the following exception: Method 'System.Object DynamicInvoke(System.Object[])' has no supported translation to SQL. Is there any solution to this problem? How far down the rabbit hole of Expression.KillMeAndMyFamily() might I have to go? To clarify why I'm doing this: I'm using T4 templates to autogenerate a simple repository and a system of pipes. Within the pipes, instead of writing: new UserPipe().Where(m => m.UserId > 10 && m.UserName.Contains("oo") && m.LastName == "Wee"); I'd like to generate something like: new UserPipe() .UserId(m => m > 10) .UserName(m => m.Contains("oo")) .LastName("Wee");

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• Sql Querying, group relationships

  - by Jordan

  Hi, Suppose I have two tables: Group ( id integer primary key, someData1 text, someData2 text ) GroupMember ( id integer primary key, group_id foreign key to Group.id, someData text ) I'm aware that my SQL syntax is not correct :) Hopefully is clear enough. My problem is this: I want to load a group record and all the GroupMember records associated with that group. As I see it, there are two options. A single query: SELECT Group.id, Group.someData1, Group.someData2 GroupMember.id, GroupMember.someData FROM Group INNER JOIN GroupMember ... WHERE Group.id = 4; Two queries: SELECT id, someData2, someData2 FROM Group WHERE id = 4; SELECT id, someData FROM GroupMember WHERE group_id = 4; The first solution has the advantage of only being one database round trip, but has the disadvantage of returning redundant data (All group data is duplicated for every group member) The second solution returns no duplicate data but involves two round trips to the database. What is preferable here? I suppose there's some threshold such that if the group sizes become sufficiently large, the cost of returning all the redundant data is going to be greater than the overhead involved with an additional database call. What other things should I be thinking about here? Thanks, Jordan

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• SQL - Count grouped entries and then get the max values grouped by date

  - by Marcus

  hello, I am out of any logic how to write the right sql statment. I've got a sqlite table holding every played track in a row with played date/time Now I will count the plays of all artists, grouped by day and then find the artist with the max playcount per day. I used this Query SELECT COUNT(ARTISTID) AS artistcount, ARTIST AS artistname,strftime('%Y-%m-%d', playtime) AS day_played FROM playcount GROUP BY artistname to get this result "93"|"The Skygreen Leopards"|"2010-06-16" "2" |"Arcade Fire" |"2010-06-15" "2" |"Dead Kennedys" |"2010-06-15" "2" |"Wolf People" |"2010-06-15" "3" |"16 Horsepower" |"2010-06-15" "3" |"Alela Diane" |"2010-06-15" "46"|"Motorama" |"2010-06-15" "1" |"Ariel Pink's Haunted" |"2010-06-14" I tried then to query this virtual table but I always get false results in artistname. SELECT MAX(artistcount), artistname , day_played FROM ( SELECT COUNT(ARTISTID) AS artistcount, ARTIST AS artistname,strftime('%Y-%m-%d', playtime) AS day_played FROM playcount GROUP BY artistname ) GROUP BY strftime('%Y-%m-%d',day_played) result in this "93"|"lilium" |"2010-06-16" "46"|"Wolf People"|"2010-06-15" "30"|"of Montreal"|"2010-06-14" but the artist name is false. I think through the grouping by day, it just use the last artist, or so. I tested stuff like INNER JOIN or GROUP BY ... HAVING in trial and error, I read examples of similar issues but always get lost in columnnames and stuff (I am a bit burned out) I hope someone can give me a hint. thanks m

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• Storing statistics of multple data types in SQL Server 2008

  - by Mike

  I am creating a statistics module in SQL Server 2008 that allows users to save data in any number of formats (date, int, decimal, percent, etc...). Currently I am using a single table to store these values as type varchar, with an extra field to denote the datatype that it should be. When I display the value, I use that datatype field to format it. I use sprocs to calculate the data for reporting; and the datatype field to convert to the appropriate datatype for the appropriate calculations. This approach works, but I don't like storing all kinds of data in a varchar field. The only alternative that I can see is to have separate tables for each datatype I want to store, and save the record information to the appropriate table based on datatype. To retreive, I run a case statement to join the appropriate table and get the data. This seems to solve. This however, seems like a lot of work for ... what gain? Wondering if I'm missing something here. Is there a better way to do this? Thanks in advance!

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• MDX equivalent to SQL subqueries with aggregation

  - by James Lampe

  I'm new to MDX and trying to solve the following problem. Investigated calculated members, subselects, scope statements, etc but can't quite get it to do what I want. Let's say I'm trying to come up with the MDX equivalent to the following SQL query: SELECT SUM(netMarketValue) net, SUM(CASE WHEN netMarketValue > 0 THEN netMarketValue ELSE 0 END) assets, SUM(CASE WHEN netMarketValue < 0 THEN netMarketValue ELSE 0 END) liabilities, SUM(ABS(netMarketValue)) gross someEntity1 FROM ( SELECT SUM(marketValue) netMarketValue, someEntity1, someEntity2 FROM <some set of tables> GROUP BY someEntity1, someEntity2) t GROUP BY someEntity1 In other words, I have an account ledger where I hide internal offsetting transactions (within someEntity2), then calculate assets & liabilities after aggregating them by someEntity2. Then I want to see the grand total of those assets & liabilities aggregated by the bigger entity, someEntity1. In my MDX schema I'd presumably have a cube with dimensions for someEntity1 & someEntity2, and marketValue would be my fact table/measure. I suppose i could create another DSV that did what my subquery does (calculating net), and simply create a cube with that as my measure dimension, but I wonder if there is a better way. I'd rather not have 2 cubes (one for these net calculations and another to go to a lower level of granularity for other use cases), since it will be a lot of duplicate info in my database. These will be very large cubes.

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• SQL Server insert with XML parameter - empty string not converting to null for numeric

  - by Mayo

  I have a stored procedure that takes an XML parameter and inserts the "Entity" nodes as records into a table. This works fine unless one of the numeric fields has a value of empty string in the XML. Then it throws an "error converting data type nvarchar to numeric" error. Is there a way for me to tell SQL to convert empty string to null for those numeric fields in the code below? -- @importData XML <- stored procedure param DECLARE @l_index INT EXECUTE sp_xml_preparedocument @l_index OUTPUT, @importData INSERT INTO dbo.myTable ( [field1] ,[field2] ,[field3] ) SELECT [field1] ,[field2] ,[field3] FROM OPENXML(@l_index, 'Entities/Entity', 1) WITH ( field1 int 'field1' ,field2 varchar(40) 'field2' ,field3 decimal(15, 2) 'field3' ) EXECUTE sp_xml_removedocument @l_index EDIT: And if it helps, sample XML. Error is thrown unless I comment out field3 in the code above or provide a value in field3 below. <?xml version="1.0" encoding="utf-16"?> <Entities> <Entity> <field1>2435</field1> <field2>843257-3242</field2> <field3 /> </Entity> </Entities>

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• SQL Joining on a one-to-many relationship

  - by Harley

  Ok, here was my original question; Table one contains ID|Name 1 Mary 2 John Table two contains ID|Color 1 Red 1 Blue 2 Blue 2 Green 2 Black I want to end up with is ID|Name|Red|Blue|Green|Black 1 Mary Y Y 2 John Y Y Y It seems that because there are 11 unique values for color and 1000's upon 1000's of records in table one that there is no 'good' way to do this. So, two other questions. Is there an efficient way to query to get this result? I can then create a crosstab in my application to get the desired result. ID|Name|Color 1 Mary Red 1 Mary Blue 2 John Blue 2 John Green 2 John Black If I wanted to limit the number of records returned how could I do a query to do something like this? Where ((color='blue') AND (color<>'red' OR color<>'green')) So using the above example I would then get back ID|Name|Color 1 Mary Blue 2 John Blue 2 John Black I connect to Visual FoxPro tables via ADODB to use SQL. Thanks!

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• LINQ 2 SQL: Partial Classes

  - by Refracted Paladin

  I need to set the ConnectionString for my DataContext's based on an AppSetting. I am trying to do this by creating a Partial Class for each DataContext. The below is what I have so far and I am wondering if I am overlooking something? Specifically, am I dealing with my DataContext's correctly(disposing, staleness, etc)? Doing it this way will I have issues with Updates and Inserts? Is the file BLLAspnetdb.cs useful or neccessary in the least or should all of that be in the generated partial class AspnetdbDataContext file? In short, is this an acceptable structure or will this cause me issues as I elaborate it? dbml File Name = Aspnetdb.dbml Partial Class File Name = Aspnetdb.cs partial class AspnetdbDataContext { public static bool IsDisconnectedUser { get { return Convert.ToBoolean(ConfigurationManager.AppSettings["IsDisconnectedUser"]) == true; } } public static AspnetdbDataContext New { get { var cs = IsDisconnectedUser ? Settings.Default.Central_aspnetdbConnectionString : Settings.Default.aspnetdbConnectionString; return new AspnetdbDataContext(cs); } } } My Created File Name = BLLAspnetdb.cs public class BLLAspnetdb { public static IList WorkerList(Guid userID) { var DB = AspnetdbDataContext.New; var workers = from user in DB.tblDemographics where user.UserID == userID select new { user.FirstName, user.LastName, user.Phone }; IList theWorkers = workers.ToList(); return theWorkers; } public static String NurseName(Guid? userID) { var DB = AspnetdbDataContext.New; var nurseName = from demographic in DB.tblDemographics where demographic.UserID == userID select demographic.FirstName +" " + demographic.LastName; return nurseName.SingleOrDefault(); } public static String SocialWorkerName(Guid? userID) { var DB = AspnetdbDataContext.New; var swName = from demographic in DB.tblDemographics where demographic.UserID == userID select demographic.FirstName + " " + demographic.LastName; return swName.SingleOrDefault(); } } see this previous question and the accepted answer for background on how I got to here... switch-connectionstrings-between-local-and-remote-with-linq-to-sql

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• SQL SERVER 2008 JOIN hints

  - by Nai

  Hi all, Recently, I was trying to optimise this query UPDATE Analytics SET UserID = x.UserID FROM Analytics z INNER JOIN UserDetail x ON x.UserGUID = z.UserGUID Estimated execution plan show 57% on the Table Update and 40% on a Hash Match (Aggregate). I did some snooping around and came across the topic of JOIN hints. So I added a LOOP hint to my inner join and WA-ZHAM! The new execution plan shows 38% on the Table Update and 58% on an Index Seek. So I was about to start applying LOOP hints to all my queries until prudence got the better of me. After some googling, I realised that JOIN hints are not very well covered in BOL. Therefore... Can someone please tell me why applying LOOP hints to all my queries is a bad idea. I read somewhere that a LOOP JOIN is default JOIN method for query optimiser but couldn't verify the validity of the statement? When are JOIN hints used? When the sh*t hits the fan and ghost busters ain't in town? What's the difference between LOOP, HASH and MERGE hints? BOL states that MERGE seems to be the slowest but what is the application of each hint? Thanks for your time and help people! I'm running SQL Server 2008 BTW. The statistics mentioned above are ESTIMATED execution plans.

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• SQL - Converting 24-hour ("military") time (2145) to "AM/PM time" (9:45 pm)

  - by CheeseConQueso

  I have 2 fields I'm working with that are stored as smallint military structured times. Edit I'm running on IBM Informix Dynamic Server Version 10.00.FC9 beg_tm and end_tm Sample values beg_tm 545 end_tm 815 beg_tm 1245 end_tm 1330 Sample output beg_tm 5:45 am end_tm 8:15 am beg_tm 12:45 pm end_tm 1:30 pm I had this working in Perl, but I'm looking for a way to do it with SQL and case statements. Is this even possible? EDIT Essentially, this formatting has to be used in an ACE report. I couldn't find a way to format it within the output section using simple blocks of if(beg_tm>=1300) then beg_tm = vbeg_tm - 1200 Where vbeg_tm is a declared char(4) variable EDIT This works for hours =1300 (EXCEPT FOR 2230 !!) select substr((beg_tm-1200),0,1)||":"||substr((beg_tm-1200),2,2) from mtg_rec where beg_tm>=1300; This works for hours < 1200 (sometimes.... 10:40 is failing) select substr((mtg_rec.beg_tm),0,(length(cast(beg_tm as varchar(4)))-2))||":"||(substr((mtg_rec.beg_tm),2,2))||" am" beg_tm from mtg_rec where mtg_no = 1; EDIT Variation of casting syntax used in Jonathan Leffler's expression approach SELECT beg_tm, cast((MOD(beg_tm/100 + 11, 12) + 1) as VARCHAR(2)) || ':' || SUBSTRING(cast((MOD(beg_tm, 100) + 100) as CHAR(3)) FROM 2) || SUBSTRING(' am pm' FROM (MOD(cast((beg_tm/1200) as INT), 2) * 3) + 1 FOR 3), end_tm, cast((MOD(end_tm/100 + 11, 12) + 1) as VARCHAR(2)) || ':' || SUBSTRING(cast((MOD(end_tm, 100) + 100) as CHAR(3)) FROM 2) || SUBSTRING(' am pm' FROM (MOD(cast((end_tm/1200) as INT), 2) * 3) + 1 FOR 3) FROM mtg_rec where mtg_no = 39;

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• noSQL/SQL/RoR: Trying to build scalable ratings table for the game

  - by alexeypro

  I am trying to solve complex thing (as it looks to me). I have next entities: PLAYER (few of them, with names like "John", "Peter", etc.). Each has unique ID. For simplicity let's think it's their name. GAME (few of them, say named "Hide and Seek", "Jump and Run", etc.). Same - each has unique ID. For simplicity of the case let it be it's name for now. SCORE (it's numeric). So, how it works. Each PLAYER can play in multiple GAMES. He gets some SCORE in every GAME. I need to build rating table -- and not one! Table #1: most played GAMES Table #2: best PLAYERS in all games (say the total SCORE in every GAME). Table #3: best PLAYERS per GAME (by SCORE in particularly that GAME). I could be build something straight right away, but that will not work. I will have more than 10,000 players; and 15 games, which will grow for sure. Score can be as low as 0, and as high as 1,000,000 (not sure if higher is possible at this moment) for player in the game. So I really need some relative data. Any suggestions? I am planning to do it with SQL, but may be just using it for key-value storage; anything -- any ideas are welcome. Thank you!

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• Dynamic where clause using Linq to SQL in a join query in a MVC application

  - by jhoefnagels

  Dear .Net Linq experts, I am looking for a way to query for products in a catalog using filters on properties which have been assigned to the product based on the category to which the product belongs. So I have the following entities involved: Products -Id -CategoryId Categories [Id] Properties [Id, CategoryId] PropertyValues [Id, PropertyId] ProductProperties [ProductId, PropertyValueId] When I ad a product to the catalog, multiple ProductProperties will be added based on the category and I would like to be able to filter all products from a category by selecting values for one or more properties. I will gather all filters, which I will hold in a list, by reading the URL. Now it is time to actually get the products based on multiple properties and I have been trying to find the right strategy but untill now it does not really work. Is there a way to make this work without writing SQL? I was trying something like this: productsInCategory = ProductRepository.Where(p => p.Category.Name == category); foreach (PropertyFilter pf in filterList) { productsInCategory = (from product in productsInCategory join pp in ProductPropertyRepository on product.Id equals pp.ProductId where pp.PropertyValueId == pf.ValueId select product); }

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• SQL Server Trouble with Rails

  - by Earlz

  Ok, I've been trying to get this to work like all day now and I'm barely any further from when I started. I'm trying to get Ruby On Rails to connect to SQL Server. I've installed unixODBC and configured it and FreeTDS and installed just about every Ruby gem relating to ODBC that exists. [earlz@earlzarch myproject]$ tsql -S AVP1 -U sa -P pass locale is "en_US.UTF-8" locale charset is "UTF-8" 1> quit [earlz@earlzarch myproject]$ isql AVP1 sa pass [ISQL]ERROR: Could not SQLConnect [earlz@earlzarch myproject]$ rake db:version (in /home/earlz/myproject) rake aborted! IM002 (0) [unixODBC][Driver Manager]Data source name not found, and no default driver specified (See full trace by running task with --trace) so, as you can see, tsql works, but not isql. What is the difference in the two that breaks it? /etc/odbc.ini [AVP1] Description = ODBC connection via FreeTDS Driver = TDS Servername = my.server UID = sa PWD = pass port = 1232 Database = mydatabase /etc/odbcinst.ini [TDS] Description = v0.6 with protocol v7.0 Driver = /usr/lib/libtdsodbc.so Setup = /usr/lib/libtdsS.so CPTimeout = CPReuse = FileUsage = 1 (and yes, I've made sure that the .so files exist) the relevant part in freetds.conf [AVP1] host = my.server port = 1232 tds version = 8.0 and finally, my database.yml development: adapter: sqlserver mode: odbc dsn: AVP1 username: sa password: pass Can anyone please help me before I pull all my hair out? I am using a 64 bit Arch Linux that is completely up to date.

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• SQL Compact allow only one WCF Client

  - by Andreas Hoffmann

  Hi, I write a little Chat Application. To save some infos like Username and Password I store the Data in an SQL-Compact 3.5 SP1 Database. Everything working fine, but If another (the same .exe on the same machine) Client want to access the Service. It came an EndpointNotFound exception, from the ServiceReference.Class.Open() at the Second Client. So i remove the CE Data Access Code and I get no Error (with an if (false)) Where is the Problem? I googled for this, but no one seems the same error I get :( SOLUTION I used the wrapper in http://csharponphone.blogspot.com/2007/01/keeping-sqlceconnection-open-and-thread.html for threat safty, and now it works :) Client Code: public test() { var newCompositeType = new Client.ServiceReference1.CompositeType(); newCompositeType.StringValue = "Hallo" + DateTime.Now.ToLongTimeString(); newCompositeType.Save = (Console.ReadKey().Key == ConsoleKey.J); ServiceReference1.Service1Client sc = new Client.ServiceReference1.Service1Client(); sc.Open(); Console.WriteLine("Save " + newCompositeType.StringValue); sc.GetDataUsingDataContract(newCompositeType); sc.Close(); } Server Code public CompositeType GetDataUsingDataContract(CompositeType composite) { if (composite.Save) { SqlCeConnection con = new SqlCeConnection(Properties.Settings.Default.Con); con.Open(); var com = con.CreateCommand(); com.CommandText = "SELECT * FROM TEST"; SqlCeResultSet result = com.ExecuteResultSet(ResultSetOptions.Scrollable | ResultSetOptions.Updatable); var rec = result.CreateRecord(); rec["TextField"] = composite.StringValue; result.Insert(rec); result.Close(); result.Dispose(); com.Dispose(); con.Close(); con.Dispose(); } return composite; }

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• refactor LINQ TO SQL custom properties that instantiate datacontext

  - by Thiago Silva

  I am working on an existing ASP.NET MVC app that started small and has grown with time to require a good re-architecture and refactoring. One thing that I am struggling with is that we've got partial classes of the L2S entities so we could add some extra properties, but these props create a new data context and query the DB for a subset of data. This would be the equivalent to doing the following in SQL, which is not a very good way to write this query as oppsed to joins: SELECT tbl1.stuff, (SELECT nestedValue FROM tbl2 WHERE tbl2.Foo = tbl1.Bar), tbl1.moreStuff FROM tbl1 so in short here's what we've got in some of our partial entity classes: public partial class Ticket { public StatusUpdate LastStatusUpdate { get { //this static method call returns a new DataContext but needs to be refactored var ctx = OurDataContext.GetContext(); var su = Compiled_Query_GetLastUpdate(ctx, this.TicketId); return su; } } } We've got some functions that create a compiled query, but the issue is that we also have some DataLoadOptions defined in the DataContext, and because we instantiate a new datacontext for getting these nested property, we get an exception "Compiled Queries across DataContexts with different LoadOptions not supported" . The first DataContext is coming from a DataContextFactory that we implemented with the refactorings, but this second one is just hanging off the entity property getter. We're implementing the Repository pattern in the refactoring process, so we must stop doing stuff like the above. Does anyone know of a good way to address this issue?

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• SQL deadlock on delete then bulk insert

  - by StarLite

  I have an issue with a deadlock in SQL Server that I haven't been able to resolve. Basically I have a large number of concurrent connections (from many machines) that are executing transactions where they first delete a range of entries and then re-insert entries within the same range with a bulk insert. Essentially, the transaction looks like this BEGIN TRANSACTION T1 DELETE FROM [TableName] WITH( XLOCK HOLDLOCK ) WHERE [Id]=@Id AND [SubId]=@SubId INSERT BULK [TableName] ( [Id] Int , [SubId] Int , [Text] VarChar(max) COLLATE SQL_Latin1_General_CP1_CI_AS ) WITH(CHECK_CONSTRAINTS, FIRE_TRIGGERS) COMMIT TRANSACTION T1 The bulk insert only inserts items matching the Id and SubId of the deletion in the same transaction. Furthermore, these Id and SubId entries should never overlap. When I have enough concurrent transaction of this form, I start to see a significant number of deadlocks between these statements. I added the locking hints XLOCK HOLDLOCK to attempt to deal with the issue, but they don't seem to be helpling. The canonical deadlock graph for this error shows: Connection 1: Holds RangeX-X on PK_TableName Holds IX Page lock on the table Requesting X Page lock on the table Connection 2: Holds IX Page lock on the table Requests RangeX-X lock on the table What do I need to do in order to ensure that these deadlocks don't occur. I have been doing some reading on the RangeX-X locks and I'm not sure I fully understand what is going on with these. Do I have any options short of locking the entire table here?

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• Linq to sql DataContext cannot set load options after results been returned

  - by David Liddle

  I have two tables A and B with a one-to-many relationship respectively. On some pages I would like to get a list of A objects only. On other pages I would like to load A with objects in B attached. This can be handled by setting the load options DataLoadOptions options = new DataLoadOptions(); options.LoadWith<A>(a => a.B); dataContext.LoadOptions = options; The trouble occurs when I first of all view all A's with load options, then go to edit a single A (do not use load options), and after edit return to the previous page. I understand why the error is occurring but not sure how to best get round this problem. I would like the DataContext to be loaded up per request. I thought I was achieving this by using StructureMap to load up my DataContext on a per request basis. This is all part of an n-tier application where my Controllers call Services which in turn call Repositories. ForRequestedType<MyDataContext>() .CacheBy(InstanceScope.PerRequest) .TheDefault.Is.Object(new MyDataContext()); ForRequestedType<IAService>() .TheDefault.Is.OfConcreteType<AService>(); ForRequestedType<IARepository>() .TheDefault.Is.OfConcreteType<ARepository>(); Here is a brief outline of my Repository public class ARepository : IARepository { private MyDataContext db; public ARepository(MyDataContext context) { db = context; } public void SetLoadOptions(DataLoadOptions options) { db.LoadOptions = options; } public IQueryable<A> Get() { return from a in db.A select a; } So my ServiceLayer, on View All, sets the load options and then gets all A's. On editing A my ServiceLayer should spin up a new DataContext and just fetch a list of A's. When sql profiling, I can see that when I go to the Edit page it is requesting A with B objects.

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• Help me with DB design

  - by eugeneK

  Hi, i'm developing text ads system. Some small clone of Google Ads. Here is diagram with common tables. Basically make it short, advertiser can have up to 10 variant of same campaign with different text variations, can geo-target his ads and unique impressions count only for IP that haven't been on certain site for more than 24 hours. Pretty simple but the question is what i lack in here from your experience because later it would much harder to fix design flaws and some of you probably done something alike also many SQL gurus in here so maybe i did over normalized DB or did not normalized as needed ? Second question is. My end goal is to get ads for user from ie. Germany that haven't seen same ad on same site for 24 hours as long as ads fit country of user. Each impression is count same as each click if there is one. I need to get 5 "random" ads based on IP, Country and higher CPC (pay per click). How can i achieve this with current design or maybe to design database the way it would be easy to get ads and show stats for advirtisers... thanks for any help...

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• LINQ-To-SQL and Mapping Table Deletions

  - by Jake

  I have a many-to-many relationship between two tables, let's say Friends and Foods. If a friend likes a food I stick a row into the FriendsFoods table, like this: ID Friend Food 1 'Tom' 'Pizza' FriendsFoods has a Primary Key 'ID', and two non-null foreign keys 'Friend' and 'Food' to the 'Friends' and 'Foods' tables, respectively. Now suppose I have a Friend tom .NET object corresponding to 'Tom', and Tom no longer likes pizza (what is wrong with him?) FriendsFoods ff = tblFriendsFoods.Where(x => x.Friend.Name == 'Tom' && x.Food.Name == 'Pizza').Single(); tom.FriendsFoods.Remove(ff); pizza.FriendsFoods.Remove(ff); If I try to SubmitChanges() on the DataContext, I get an exception because it attempts to insert a null into the Friend and Food columns in the FriendsFoods table. I'm sure I can put together some kind of convoluted logic to track changes to the FriendsFoods table, intercept SubmitChanges() calls, etc to try and get this to work the way I want, but is there a nice, clean way to remove a Many-To-Many relationship with LINQ-To-SQL?

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• Beginner SQL question: querying gold and silver tag badges in Stack Exchange Data Explorer

  - by polygenelubricants

  I'm using the Stack Exchange Data Explorer to learn SQL, but I think the fundamentals of the question is applicable to other databases. I'm trying to query the Badges table, which according to Stexdex (that's what I'm going to call it from now on) has the following schema: Badges Id UserId Name Date This works well for badges like [Epic] and [Legendary] which have unique names, but the silver and gold tag-specific badges seems to be mixed in together by having the same exact name. Here's an example query I wrote for [mysql] tag: SELECT UserId as [User Link], Date FROM Badges Where Name = 'mysql' Order By Date ASC The (slightly annotated) output is: as seen on stexdex: User Link Date --------------- ------------------- // all for silver except where noted Bill Karwin 2009-02-20 11:00:25 Quassnoi 2009-06-01 10:00:16 Greg 2009-10-22 10:00:25 Quassnoi 2009-10-31 10:00:24 // for gold Bill Karwin 2009-11-23 11:00:30 // for gold cletus 2010-01-01 11:00:23 OMG Ponies 2010-01-03 11:00:48 Pascal MARTIN 2010-02-17 11:00:29 Mark Byers 2010-04-07 10:00:35 Daniel Vassallo 2010-05-14 10:00:38 This is consistent with the current list of silver and gold earners at the moment of this writing, but to speak in more timeless terms, as of the end of May 2010 only 2 users have earned the gold [mysql] tag: Quassnoi and Bill Karwin, as evidenced in the above result by their names being the only ones that appear twice. So this is the way I understand it: The first time an Id appears (in chronological order) is for the silver badge The second time is for the gold Now, the above result mixes the silver and gold entries together. My questions are: Is this a typical design, or are there much friendlier schema/normalization/whatever you call it? In the current design, how would you query the silver and gold badges separately? GROUP BY Id and picking the min/max or first/second by the Date somehow? How can you write a query that lists all the silver badges first then all the gold badges next? Imagine also that the "real" query may be more complicated, i.e. not just listing by date. How would you write it so that it doesn't have too many repetition between the silver and gold subqueries? Is it perhaps more typical to do two totally separate queries instead? What is this idiom called? A row "partitioning" query to put them into "buckets" or something?

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• Comparing RPG to C# and SQL.

  - by Kevin

  In an RPG program (One of IBM's languages on the AS/400) I can "chain" out to a file to see if a record (say, a certain customer record) exists in the file. If it does, then I can update that record instantly with new data. If the record doesn't exist, I can write a new record. The code would look like this: Customer Chain CustFile 71 ;turn on indicator 71 if not found if *in71 ;if 71 is "on" eval CustID = Customer; eval CustCredit = 10000; write CustRecord else ;71 not on, record found. CustCredit = 10000; update CustRecord endif Not being real familiar with SQL/C#, I'm wondering if there is a way to do a random retrieval from a file (which is what "chain" does in RPG). Basically I want to see if a record exists. If it does, update the record with some new information. If it does not, then I want to write a new record. I'm sure it's possible, but not quite sure how to go about doing it. Any advice would be greatly appreciated.

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• SQL Joining Two or More from Table B with Common Data in Table A

  - by Matthew Frederick

  The real-world situation is a series of events that each have two or more participants (like sports teams, though there can be more than two in an event), only one of which is the host of the event. There is an Event db table for each unique event and a Participant db table with unique participants. They are joined together using a Matchup table. They look like this: Event EventID (PK) (other event data like the date, etc.) Participant ParticipantID (PK) Name Matchup EventID (FK to Event table) ParicipantID (FK to Participant) Host (1 or 0, only 1 host = 1 per EventID) What I'd like to get as a result is something like this: EventID ParticipantID where host = 1 Participant.Name where host = 1 ParticipantID where host = 0 Participant.Name where host = 0 ParticipantID where host = 0 Participant.Name where host = 0 ... Where one event has 2 participants and another has 3 participants, for example, the third participant column data would be null or otherwise noticeable, something like (PID = ParticipantID): EventID PID-1(host) Name-1 (host) PID-2 Name-2 PID-3 Name-3 ------- ----------- ------------- ----- ------ ----- ------ 1 7 Lions 8 Tigers 12 Bears 2 11 Dogs 9 Cats NULL NULL I suspect the answer is reasonably straightforward but for some reason I'm not wrapping my head around it. Alternately it's very difficult. :) I'm using MYSQL 5 if that affects the available SQL.

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• sql server 2005 stored procedure unexpected behaviour

  - by user283405

  i have written a simple stored procedure (run as job) that checks user subscribe keyword alerts. when article posted the stored procedure sends email to those users if the subscribed keyword matched with article title. One section of my stored procedure is: OPEN @getInputBuffer FETCH NEXT FROM @getInputBuffer INTO @String WHILE @@FETCH_STATUS = 0 BEGIN --PRINT @String INSERT INTO #Temp(ArticleID,UserID) SELECT A.ID,@UserID FROM CONTAINSTABLE(Question,(Text),@String) QQ JOIN Article A WITH (NOLOCK) ON A.ID = QQ.[Key] WHERE A.ID > @ArticleID FETCH NEXT FROM @getInputBuffer INTO @String END CLOSE @getInputBuffer DEALLOCATE @getInputBuffer This job run every 5 minute and it checks last 50 articles. It was working fine for last 3 months but a week before it behaved unexpectedly. The problem is that it sends irrelevant results. The @String contains user alert keyword and it matches to the latest articles using Full text search. The normal execution time is 3 minutes but its execution time is 3 days (in problem). Now the current status is its working fine but we are unable to find any reason why it sent irrelevant results. Note: I am already removing noise words from user alert keyword. I am using SQL Server 2005 Enterprise Edition.

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• Optimize an SQL statement

  - by kovshenin

  Hey, I'm running WordPress, the database diagram could be found here: http://codex.wordpress.org/Database_Description After doing tonnes of filters and applying some hooks to the core, I'm left with the following query: SELECT SQL_CALC_FOUND_ROWS wp_posts.* FROM wp_posts JOIN wp_postmeta ppmeta_beds ON (ppmeta_beds.post_id = wp_posts.ID AND ppmeta_beds.meta_key = 'pp-general-beds' AND ppmeta_beds.meta_value >= 2) JOIN wp_postmeta ppmeta_baths ON (ppmeta_baths.post_id = wp_posts.ID AND ppmeta_baths.meta_key = 'pp-general-baths' AND ppmeta_baths.meta_value >= 3) JOIN wp_postmeta ppmeta_furnished ON (ppmeta_furnished.post_id = wp_posts.ID AND ppmeta_furnished.meta_key = 'pp-general-furnished' AND ppmeta_furnished.meta_value = 'yes') JOIN wp_postmeta ppmeta_pool ON (ppmeta_pool.post_id = wp_posts.ID AND ppmeta_pool.meta_key = 'pp-facilities-pool' AND ppmeta_pool.meta_value = 'yes') JOIN wp_postmeta ppmeta_pool_type ON (ppmeta_pool_type.post_id = wp_posts.ID AND ppmeta_pool_type.meta_key = 'pp-facilities-pool-type' AND ppmeta_pool_type.meta_value IN ('tennis', 'voleyball', 'basketball', 'fitness')) JOIN wp_postmeta ppmeta_sport ON (ppmeta_sport.post_id = wp_posts.ID AND ppmeta_sport.meta_key = 'pp-facilities-sport' AND ppmeta_sport.meta_value = 'yes') JOIN wp_postmeta ppmeta_sport_type ON (ppmeta_sport_type.post_id = wp_posts.ID AND ppmeta_sport_type.meta_key = 'pp-facilities-sport-type' AND ppmeta_sport_type.meta_value IN ('tennis', 'voleyball', 'basketball', 'fitness')) JOIN wp_postmeta ppmeta_parking ON (ppmeta_parking.post_id = wp_posts.ID AND ppmeta_parking.meta_key = 'pp-facilities-parking' AND ppmeta_parking.meta_value = 'yes') JOIN wp_postmeta ppmeta_parking_type ON (ppmeta_parking_type.post_id = wp_posts.ID AND ppmeta_parking_type.meta_key = 'pp-facilities-parking-type' AND ppmeta_parking_type.meta_value IN ('street', 'off-street', 'garage')) JOIN wp_postmeta ppmeta_garden ON (ppmeta_garden.post_id = wp_posts.ID AND ppmeta_garden.meta_key = 'pp-facilities-garden' AND ppmeta_garden.meta_value = 'yes') JOIN wp_postmeta ppmeta_garden_type ON (ppmeta_garden_type.post_id = wp_posts.ID AND ppmeta_garden_type.meta_key = 'pp-facilities-garden-type' AND ppmeta_garden_type.meta_value IN ('private', 'communal')) JOIN wp_postmeta ppmeta_type ON (ppmeta_type.post_id = wp_posts.ID AND ppmeta_type.meta_key = 'pp-general-type' AND ppmeta_type.meta_value IN ('villa', 'apartment', 'penthouse')) JOIN wp_postmeta ppmeta_status ON (ppmeta_status.post_id = wp_posts.ID AND ppmeta_status.meta_key = 'pp-general-status' AND ppmeta_status.meta_value IN ('off-plan', 'resale')) JOIN wp_postmeta ppmeta_location_type ON (ppmeta_location_type.post_id = wp_posts.ID AND ppmeta_location_type.meta_key = 'pp-location-type' AND ppmeta_location_type.meta_value IN ('beachfront', 'countryside', 'town-center', 'near-the-sea', 'hillside', 'private-resort')) JOIN wp_postmeta ppmeta_price_range ON (ppmeta_price_range.post_id = wp_posts.ID AND ppmeta_price_range.meta_key = 'pp-general-price' AND ppmeta_price_range.meta_value BETWEEN 10000 AND 50000) JOIN wp_postmeta ppmeta_area_range ON (ppmeta_area_range.post_id = wp_posts.ID AND ppmeta_area_range.meta_key = 'pp-general-area' AND ppmeta_area_range.meta_value BETWEEN 50 AND 150) WHERE 1=1 AND (((wp_posts.post_title LIKE '%fdsfsad%') OR (wp_posts.post_content LIKE '%fdsfsad%'))) AND wp_posts.post_type = 'property' AND (wp_posts.post_status = 'publish' OR wp_posts.post_status = 'private') ORDER BY wp_posts.post_date DESC LIMIT 0, 10 It's way too big. Could anybody please show me a way of optimizing all those joins into fewer statements? As you can see they all use the same tables but under different names. I'm not an SQL guru but I think there should be a way, because this is insane ;) Thanks! Update Here's what explain returns: http://twitpic.com/1cd36p

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• Updating a Foreign Key constraint with ON DELETE CASCADE not updating?

  - by Alastair Pitts

  We've realised in our SQL Server 2005 DB that some Foreign Keys don't have the On Delete Cascade property set, which is giving us a couple of referential errors when we try and delete some records. Use the Management Studio I scripted the DROP and CREATESQL's, but it seems that the CREATE isn't working correctly. The DROP: USE [FootprintReports] GO IF EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N'[dbo].[FK__SUBSCRIPTIONS_Reports]') AND parent_object_id = OBJECT_ID(N'[dbo].[_SUBSCRIPTIONS]')) ALTER TABLE [dbo].[_SUBSCRIPTIONS] DROP CONSTRAINT [FK__SUBSCRIPTIONS_Reports] and the CREATE USE [FootprintReports] GO ALTER TABLE [dbo].[_SUBSCRIPTIONS] WITH CHECK ADD CONSTRAINT [FK__SUBSCRIPTIONS_Reports] FOREIGN KEY([PARAMETER_ReportID]) REFERENCES [dbo].[Reports] ([ID]) ON DELETE CASCADE GO ALTER TABLE [dbo].[_SUBSCRIPTIONS] CHECK CONSTRAINT [FK__SUBSCRIPTIONS_Reports] If I manually change the value of the On Delete in the GUI, after dropping and recreating, the On Delete isn't correctly updated. As a test, I set the Delete rule in the GUI to Set Null. It dropped correctly, and recreated without error. If I got back into the GUI, it is still showing the Set Null as the Delete Rule. Have I done something wrong? or is there another way to edit a constraint to add the ON DELETE CASCADE rule?

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