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  • C# Joins/Where with Linq and Lambda

    - by David
    Hello, I'm having trouble with a query written in Linq and Lambda. So far, I'm getting allot of errors here's my code: int id = 1; var query = database.Posts.Join(database.Post_Metas, post => database.Posts.Where(x => x.ID == id), meta => database.Post_Metas.Where(x => x.Post_ID == id), (post, meta) => new { Post = post, Meta = meta }); I'm new to using Linq, so I'm not sure if this query is correct.

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  • Sort and Group in LINQ

    - by Jono
    I apologise in advance if this has been answered before; it seems so fundamental to me yet I haven't turned up the answer in any of my searches. I have a list of string tuples, say (P1,P2) I'd like to know if there's a LINQ statement where I could group by P1 (in ascending order), and have that group contain all the P2 values for the group (in descending order). For input: ("A","B"), ("A","C"), ("D","B") I'd like to get two groups: "A" and "D" (in that order, every time) where group "A" contains "C" and "B" (in that order, every time) and group "D" contains, well, "B". Is this possible with the built-in LINQ classes or do I need to iterate the groups and sort them myself? Sounds like hard work~

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  • Many-To-Many Query with Linq-To-NHibernate

    - by rjygraham
    Ok guys (and gals), this one has been driving me nuts all night and I'm turning to your collective wisdom for help. I'm using Fluent Nhibernate and Linq-To-NHibernate as my data access story and I have the following simplified DB structure: CREATE TABLE [dbo].[Classes]( [Id] [bigint] IDENTITY(1,1) NOT NULL, [Name] [nvarchar](100) NOT NULL, [StartDate] [datetime2](7) NOT NULL, [EndDate] [datetime2](7) NOT NULL, CONSTRAINT [PK_Classes] PRIMARY KEY CLUSTERED ( [Id] ASC ) CREATE TABLE [dbo].[Sections]( [Id] [bigint] IDENTITY(1,1) NOT NULL, [ClassId] [bigint] NOT NULL, [InternalCode] [varchar](10) NOT NULL, CONSTRAINT [PK_Sections] PRIMARY KEY CLUSTERED ( [Id] ASC ) CREATE TABLE [dbo].[SectionStudents]( [SectionId] [bigint] NOT NULL, [UserId] [uniqueidentifier] NOT NULL, CONSTRAINT [PK_SectionStudents] PRIMARY KEY CLUSTERED ( [SectionId] ASC, [UserId] ASC ) CREATE TABLE [dbo].[aspnet_Users]( [ApplicationId] [uniqueidentifier] NOT NULL, [UserId] [uniqueidentifier] NOT NULL, [UserName] [nvarchar](256) NOT NULL, [LoweredUserName] [nvarchar](256) NOT NULL, [MobileAlias] [nvarchar](16) NULL, [IsAnonymous] [bit] NOT NULL, [LastActivityDate] [datetime] NOT NULL, PRIMARY KEY NONCLUSTERED ( [UserId] ASC ) I omitted the foreign keys for brevity, but essentially this boils down to: A Class can have many Sections. A Section can belong to only 1 Class but can have many Students. A Student (aspnet_Users) can belong to many Sections. I've setup the corresponding Model classes and Fluent NHibernate Mapping classes, all that is working fine. Here's where I'm getting stuck. I need to write a query which will return the sections a student is enrolled in based on the student's UserId and the dates of the class. Here's what I've tried so far: 1. var sections = (from s in this.Session.Linq<Sections>() where s.Class.StartDate <= DateTime.UtcNow && s.Class.EndDate > DateTime.UtcNow && s.Students.First(f => f.UserId == userId) != null select s); 2. var sections = (from s in this.Session.Linq<Sections>() where s.Class.StartDate <= DateTime.UtcNow && s.Class.EndDate > DateTime.UtcNow && s.Students.Where(w => w.UserId == userId).FirstOrDefault().Id == userId select s); Obviously, 2 above will fail miserably if there are no students matching userId for classes the current date between it's start and end dates...but I just wanted to try. The filters for the Class StartDate and EndDate work fine, but the many-to-many relation with Students is proving to be difficult. Everytime I try running the query I get an ArgumentNullException with the message: Value cannot be null. Parameter name: session I've considered going down the path of making the SectionStudents relation a Model class with a reference to Section and a reference to Student instead of a many-to-many. I'd like to avoid that if I can, and I'm not even sure it would work that way. Thanks in advance to anyone who can help. Ryan

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  • LINQ-to-SQL and SQL Compact - database file sharing problem

    - by Eye of Hell
    Hello. I'm learing LINQ-to-SQL right now and i have wrote a simple application that define SQL data: [Table( Name = "items" )] public class Item { [ Column( IsPrimaryKey = true, IsDbGenerated = true ) ] public int Id; [ Column ] public string Name; } I have launched 2 copy of application connected to the same .sdf file and tested if all database modifications in one application affects another application. But strange thing arise. If i use InsertOnSubmit() and DeleteOnSubmit() in one application, added/removed items are instantly visible in other application via 'select' LINQ queue. But if i try to modify 'Name' field in one application, it is NOT visible in other applicaton until it reconnects the database :(. The test code i use: var Items = from c in db.Items where Id == c.Id select c; foreach( var Item in Items ) { Item.Name = "new name"; break; } db.SubmitChanges(); Can anyone suggest what i'm doing wrong and why InsertOnSubmit()/DeleteOnSubmit works and SubmitChanges() don't?

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  • calculate distance with linq or subsonic C# MVC

    - by minus4
    i have this MySQL statement from a search page, the user enters there postcode and it finds the nearest stiocklist within 15 MIles of the entered postcode. SELECT * , ( ( ACOS( SIN( "+SENTLNG +" * PI( ) /180 ) * SIN( s_lat * PI( ) /180 ) + COS( " + SENTLNG +" * PI( ) /180 ) * COS( s_lat * PI( ) /180 ) * COS( ( " + SENTLANG + " - s_lng ) * PI( ) /180 ) ) *180 / PI( ) ) *60 * 1.1515 ) AS distance_miles FROM new_stockists WHERE s_lat IS NOT NULL HAVING distance_miles <15 ORDER BY distance_miles ASC LIMIT 0 , 15 but now i am using linq and subsonic and not got a clue how do do this in linq or subsonic your help would be much appreciated, please also not that i have to sent in a dynamic from address, thats the postcode mentioned at the top of the page, i do a call to google to get then lng and lat from them for the postcode given.

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  • Linq to SQL EntitySet Records causing duplicate insertion

    - by Savvas Sopiadis
    In a WPF application i'm using Linq to SQL in a multi tier application. (This is an archailogy photo filing application), so every excavation has its corresponding Pictures, thus a one-to-many relationship. This relationship is correctly created by SQLMetal (which i'm using to create the POCOs). So here is the situation i 'm having trouble with: Saving changes (either of new or altered objects) is done through UnitOfWork() pattern this way: using (IUnitOfWork unitOfWork = UnitOfWork.Begin()) { //if this is a new record if (SelectedExcavation.excavation.ExcavationId == 0) { IsNewRecord = true; excavService.Add(SelectedExcavation.excavation); } //send the actual changes to the dbms unitOfWork.Commit(); } Everything works fine! BUTTTT!!! Whenever a record gets updated which has (already at least one ) corresponding Picture Record: 1) a new Excavation Record is inserted 2) the current Excavation Record gets updated 3) the previous Picture Record gets its Id changed to the newly created ExcavationId What is going on under the hood? Does Linq to SQL not handle such simple update scenarios? Thanks in advance

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  • LINQ insert to database by WCF Service from Silverlight app

    - by Rafal
    Hi I have a problem during insert to database by LINQ command in WCF Service from Silverlight application. Receiving data works fine - select works in LINQ and shows data from database(sql server 2008). When i try to insert data, the Error ocures: System.Net.WebException: The remote server returned an error: NotFound. ---> System.Net.WebException: The remote server returned an error: NotFound. at System.Net.Browser.BrowserHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult) at System.Net.Browser.BrowserHttpWebRequest.<>c__DisplayClass5.<EndGetResponse>b__4(Object sendState) at System.Net.Browser.AsyncHelper.<>c__DisplayClass2.<BeginOnUI>b__0(Object sendState) --- End of inner exception stack trace --- at System.Net.Browser.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state) at System.Net.Browser.BrowserHttpWebRequest.EndGetResponse(IAsyncResult asyncResult) at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelAsyncRequest.CompleteGetResponse(IAsyncResult result)} It looks the same, when i had a wrong ClientConfig/Web.config file. Please Help...I need to insert some data:)

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  • linq NullReferenceException while checking for null reference

    - by Odrade
    I have the following LINQ query: List<FileInputItem> inputList = GetInputList(); var results = from FileInputItem f in inputList where ( Path.GetDirectoryName(f.Folder).ToLower().Trim() == somePath || Path.GetDirectoryName(f.Folder).ToLower().Trim() == someOtherPath ) && f.Expression == null select f; Every time this query is executed, it generates a NullReferenceException. If I remove the condition f.Expression == null or change it to f.Expression != null, the query executes normally (giving the wrong results, of course). The relevant bits of FileInputItem look like this: [Serializable] public class FileInputItem { [XmlElement("Folder")] public string Folder { get; set; } [XmlElement("Expression")] public string Expression { get; set; } /*SNIP. Irrelevant properties */ } I'm new to LINQ to objects, so I'm probably missing something fundamental here. What's the deal?

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  • Linq to Entities performance within ASP.NET Development Server

    - by tster
    I've been evaluating linq to entities and linq to SQL for a project. Obviously each has its own advantages and disadvantages which have been discussed plenty of times here. However, One thing I am seeing with L2E is kind of odd. Using L2S, when using the ASP.NET Development Server, the performance is a little slower for my web service calls. I'm looking at 300ms vs. 250 ms. However, when using L2E, when using ASP.NET Dev Server, the performance is awful. I'm talking 1,250 ms vs. 220 ms. I know I should probably just use local IIS for development, but I'm curious if anyone else has seen this, or knows what is causing it.

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  • Custom Expression in Linq-to-Sql Designer

    - by csharpnoob
    According to Microsoft: http://msdn.microsoft.com/de-de/library/system.data.linq.mapping.columnattribute.expression.aspx It's possible to add expression to the Linq-to-SQL Mapping. But how to configure or add them in Visual Studio in the Designer? Problem, when I add it manual to thex XYZ.designer.cs it on change it will be lost. //------------------------------------------------------------------------------ // <auto-generated> // This code was generated by a tool. // Runtime Version:2.0.50727.4927 // // Changes to this file may cause incorrect behavior and will be lost if // the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ This is generated: [Column(Name="id", Storage="_id", DbType="Int")] public System.Nullable<int> id { ... But i need something like this [Column(Name="id", Storage="_id", DbType="Int", Expression="Max(id)")] public System.Nullable<int> id { ... Thanks.

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  • Processing a property in linq to sql

    - by Mostafa
    Hi It's my first LINQ TO SQL Project , So definitely my question could be naive . Till now I used to create new property in Business Object beside of every DateTime Property , That's because i need to do some processing in my DateTime property and show it in special string format for binding to UI Controls .Like : private DateTime _insertDate; /// /// I have "InertDate" field in my Table on Database /// public DateTime InsertDate { get { return _insertDate; } set { _insertDate = value; } } // Because i need to do some processing I create a readonly string property that pass InsertDate to Utility method and return special string Date public string PInsertDate { get { return Utility.ToSpecialDate(_insertDate); } } My question is I don't know how to do it in LINQ . I did like follow but i get run time error. ToosDataContext db = new ToosDataContext(); var newslist = from p in db.News select new {p.NewsId,p.Title,tarikh =MD.Utility.ToSpecialDate( p.ReleaseDate)}; GridView1.DataSource = newslist; GridView1.DataBind();

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  • "Cleanly" Deploying an ASP.NET Application with LINQ to SQL Server

    - by Bob Kaufman
    In my development environment, my SQL Server is PHILIP\SQLEXPRESS. In testing, it's ANNIE, and the live environment will have a third name yet to be determined. I would have assumed that updating the following statement in web.config would have been enough: <add name="MyConnectionString"providerName="System.Data.SqlClient" connectionString="Data Source=PHILIP\SQLEXPRESS;Initial Catalog=MyDtabase;Integrated Security=True" /> When using SqlConnection, SqlCommand, SqlDataReader and friends, that's all it took. Using LINQ, it doesn't seem to work that nicely. I see the servername repeated in my .dbml file as well as in Settings.settings. After changing it in all of those places, I get it to work. However if I'm doing a few deployments per day during testing, I want to avoid this regimen. My question is: is there a programmatic solution for LINQ to SQL that will allow me to specify the connection string once, preferably in web.config, and get everybody else to refer to it?

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  • Using LINQ to Obtain Max of Columns for Two Dimensional Arrays

    - by Ngu Soon Hui
    Is there anyway to use LINQ to obtain the maximum of each columns for two dimensional arrays? Assume that I have the following: var arrays = new double[5,100](); I want to get the maximum of arrays[0,:], arrays[1,:] .... arrays[4,:]. How to use LINQ to do it? I could have use such method public double GetMax(double[,] arr, int rowIndex) { var colCount = arr.GetLength(1); double max = 0.0; for(int i=0; i<colCount; i++) { max=Math.Max(Math.Abs(arr[rowIndex, i]), max); } return max; } But I would prefer a more succinct ways of doing things.

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  • calculate distance with linq or subsonic

    - by minus4
    i have this MySQL statement from a search page, the user enters there postcode and it finds the nearest stiocklist within 15 MIles of the entered postcode. SELECT * , ( ( ACOS( SIN( "+SENTLNG +" * PI( ) /180 ) * SIN( s_lat * PI( ) /180 ) + COS( " + SENTLNG +" * PI( ) /180 ) * COS( s_lat * PI( ) /180 ) * COS( ( " + SENTLANG + " - s_lng ) * PI( ) /180 ) ) *180 / PI( ) ) *60 * 1.1515 ) AS distance_miles FROM new_stockists WHERE s_lat IS NOT NULL HAVING distance_miles <15 ORDER BY distance_miles ASC LIMIT 0 , 15 but now i am using linq and subsonic and not got a clue how do do this in linq or subsonic your help would be much appreciated, please also not that i have to sent in a dynamic from address, thats the postcode mentioned at the top of the page, i do a call to google to get then lng and lat from them for the postcode given.

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  • Getting "select permission denied" when using LINQ but my account is a sysadmin

    - by Wayne M
    I have a console app that's geared to be automatically ran as a Scheduled Task. I use LINQ to SQL to pull some data out of the database, format it into a CSV and email it to a client. All of a sudden I am getting the error "SELECT permission denied for table", but the account I'm using to connect to the database (specified in my app.config file) has the "sysadmin" server role (bad programmer, I know; I'll get around to changing it to a better account later but I want to make sure it works first). I can connect directly to the SQL database using that very same account and query the table in question without a problem, it only seems to be when using the LINQ code. Any idea what would be causing this?

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  • Performance on joins in linq

    - by swapna
    HI , I am going to rewrite a store procedure in LINQ. What this sp is doing is joining 12 tables and get the data and insert it into another table. it has 7 left outer joins and 4 inner joins.And returns one row of data. Now question. 1)What is the best way to achieve this joins in linq. 2) do you think this affect performance (its only retrieving one row of data at a given point of time) Please advice. Thanks SNA.

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  • Advanced LINQ Update Statement

    - by user1902490
    I have a data base with Price_old like: Date --- Hour --- Price _____________________________ Jan 1 --- 1 --- $3.0 Jan 1 --- 2 --- $3.1 Jan 1 --- 3 --- $3.3 Jan 1 --- 4 --- $3.15 Jan 2 --- 1 --- $2.95 Jan 2 --- 2 --- $3.2 Jan 2 --- 3 --- $3.05 What I then have is a spreadsheet, with the same structure, that I will be reading into a datatable, I'll call the new datatable Price_New, note that price new may not have all the same date/hours as Price_Old So, I end up with 2 datatables, Price_Old, and Price_New, and what I need to do is update Price_old with the new prices in Price_New, and then commit those new prices to the Database. I am kinda new to LINQ (about 30 mins of experience) and would really appreciate if someone could give me a pointer or two on whether or not this is doing in LINQ and what the best method would be. Thanks

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  • querying databases on same server with linq

    - by geoff swartz
    In normal sql I could do joins on tables in different databases as long as they were on the same server (or linked servers). In linq I can't figure out how to do that. Is this possible? For example, if I have a database called db1 and another called db2. db1 has a table called people and db2 has a table called address I could do something like... select a.addressline1, p.firstname from db1.dbo.people p inner join db2.dbo.address a on p.peopleid = a.peopleid Is this possible with linq? Thanks.

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  • linq "let" translation

    - by luke
    I understand that when the C# compiler sees a linq query comprehension, it basically does a straight translation to the corresponding Linq Extension methods and lambdas. i.e. from x in list select x.property gets translated to: list.Select(x => x.property) my question is what do let clauses get translated to. for example how would this get translated by the compiler. from x in list let v = SomeComplexExpressionDependingOnx select v (p.s. i know this could be reduced to just select SomeComplexExpressionDependingOnx but i want to know how this is done in general) Thanks!

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  • Storing object as a column in LINQ

    - by Alex
    Hello, i have some class which constructs itself from string, like this: CurrencyVector v = new CurrencyVector("10 WMR / 20 WMZ"); it's actually a class which holds multiple currency values, but it does not matter much. I need to change type of column in my LINQ table (in vs 2010 designer) from String to that class, CurrencyVector. If i do it - i get runtime error when LINQ runtime tries to cast String as CurrencyVector (when populating the table from database). Adding IConvertible did not help. I wrapped these columns in properties, but it's ugly and slow solution. Searching internet gave no results.

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  • LINQ count query returns a 1 instead of a 0

    - by user335810
    I have the following view:- CREATE VIEW tbl_adjudicator_result_view AS SELECT a.adjudicator_id, sar.section_adjudicator_role_id, s.section_id, sdr.section_dance_role_id, d.dance_id, c.contact_id, ro.round_id, r.result_id, c.title, c.first_name, c.last_name, d.name, r.value, ro.type FROM tbl_adjudicator a INNER JOIN tbl_section_adjudicator_role sar on sar.section_adjudicator_role2adjudicator = a.adjudicator_id INNER JOIN tbl_section s on sar.section_adjudicator_role2section = s.section_id INNER JOIN tbl_section_dance_role sdr on sdr.section_dance_role2section = s.section_id INNER JOIN tbl_dance d on sdr.section_dance_role2dance = d.dance_id INNER JOIN tbl_contact c on a.adjudicator2contact = c.contact_id INNER JOIN tbl_round ro on ro.round2section = s.section_id LEFT OUTER JOIN tbl_result r on r.result2adjudicator = a.adjudicator_id AND r.result2dance = d.dance_id When I run the following query directly against the db I get 0 in the count column where there is no result select adjudicator_id, first_name, COUNT(result_id) from tbl_adjudicator_result_view arv where arv.round_id = 16 group by adjudicator_id, first_name However when I use LINQ query I always get 1 in the Count Column var query = from arv in db.AdjudicatorResultViews where arv.round_id == id group arv by new { arv.adjudicator_id, arv.first_name} into grp select new AdjudicatorResultViewGroupedByDance { AdjudicatorId = grp.Key.adjudicator_id, FirstName = grp.Key.first_name, Count = grp.Select(p => p.result_id).Distinct().Count() }; What do I need to change in the View / Linq query.

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  • Help needed with Linq To Sql Query

    - by fearofawhackplanet
    I have the concept of valid/ordered transitions. So for example, it's not possible to move to status In progress from status Complete. Current and Next in table StatusTransition are FK (StatusType.Id). The Linq generator has created the following relations: Child Property Name: StatusTransitions1 Parent Property Name: StatusType1 Participating Properties: StatusType.Id -> StatusTransition.Next Child Property Name: StatusTransitions Parent Property Name: StatusType Participating Properties: StatusType.Id -> StatusTransition.Current I'm normally ok with Linq but I'm having difficulty getting the list of valid Next StatusTypes from the Current status. public List<StatusType> GetValidStatusTransitions(int statusId) { // trying to write something like the following // (obviously not correct) return _statusRepository .Where(s => s.Id == statusId) .Next.StatusTypes; }

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