.net – Linq – Row not found or changed

.net-3.5linqlinq-to-sqlnet

I have the following code:

        Guid id = imageMetaData.ID;

        Data.LinqToSQL.Image dbImage = DBContext.Images.Where(x => x.ID == id).SingleOrDefault();

        dbImage.width = imageMetaData.Width;
        dbImage.height = imageMetaData.Height;

        DBContext.SubmitChanges();

Looking at SQL Profiler, the following SQL is being generated:

exec sp_executesql N'UPDATE [dbo].[Images]
SET [height] = @p0, [width] = @p1
WHERE 0 = 1',N'@p0 int,@p1 int',@p0=603,@p1=365

Why does my where statement not include a "where id=…."???

What am I doing wrong?

My application throws a ChangeConflictException with the message… "Row not found or changed"

Best Answer

Check to make sure your model matches the DB. I've run across this if they are out of sync, in most cases the nullable flag. Check out this article for a possible cause.

I assume you are using the release version of .net 3.5 (Visual Studio 2008).

Related Solutions

.net – Entity Framework vs LINQ to SQL

LINQ to SQL only supports 1 to 1 mapping of database tables, views, sprocs and functions available in Microsoft SQL Server. It's a great API to use for quick data access construction to relatively well designed SQL Server databases. LINQ2SQL was first released with C# 3.0 and .Net Framework 3.5.

LINQ to Entities (ADO.Net Entity Framework) is an ORM (Object Relational Mapper) API which allows for a broad definition of object domain models and their relationships to many different ADO.Net data providers. As such, you can mix and match a number of different database vendors, application servers or protocols to design an aggregated mash-up of objects which are constructed from a variety of tables, sources, services, etc. ADO.Net Framework was released with the .Net Framework 3.5 SP1.

This is a good introductory article on MSDN: Introducing LINQ to Relational Data

C# – LINQ query on a DataTable

You can't query against the DataTable's Rows collection, since DataRowCollection doesn't implement IEnumerable<T>. You need to use the AsEnumerable() extension for DataTable. Like so:

var results = from myRow in myDataTable.AsEnumerable()
where myRow.Field<int>("RowNo") == 1
select myRow;

And as @Keith says, you'll need to add a reference to System.Data.DataSetExtensions

AsEnumerable() returns IEnumerable<DataRow>. If you need to convert IEnumerable<DataRow> to a DataTable, use the CopyToDataTable() extension.

Below is query with Lambda Expression,

var result = myDataTable
    .AsEnumerable()
    .Where(myRow => myRow.Field<int>("RowNo") == 1);

Best Answer

Related Solutions

.net – Entity Framework vs LINQ to SQL

C# – LINQ query on a DataTable

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