Posts tagged: linq

Grouping ADO.NET DataTable using LINQ

By , December 17, 2009 10:22 am

I’ve described before how to group and aggregate data in ADO.NET data table using standard .NET 2.0 features. But if you happen to use .NET 3.5 or above and Visual Studio 2008 or above – that entire block of code can be replaced with a single LINQ query:

Function GroupBy(ByVal i_sGroupByColumn As String,  ByVal i_sAggregateColumn As String, ByVal i_dSourceTable As DataTable) As DataTable

     dim aQuery = From row In i_dSourceTable Group By Group1 = row(i_sGroupByColumn) Into Group Select Group1,  Aggr = Group.Count(Function(row) row(i_sAggregateColumn))

    return aQuery.toDataTable

End Function

The query at line 3 is a LINQ to DataSet query, so reference to System.Data.Linq has to be added to your project. The Group.Count aggregate can be replaced with Group.Max, Group.Min, Group.Sum or Group.Avg to perform respectful function.

There is one caveat though. Continue reading 'Grouping ADO.NET DataTable using LINQ'»

Method ‘System.Object CompareObjectEqual(System.Object, System.Object, Boolean)’ has no supported translation to SQL. Solution to error

By , October 1, 2009 2:15 pm

I was running a basic LINQ 2 SQL statement:

From role In db.user_role _
Where role.USER_ID = Session("user_id") Select role

when I encountered following error message:

Method ‘System.Object CompareObjectEqual(System.Object, System.Object, Boolean)’ has no supported translation to SQL.

After a little research I found the solution.
Continue reading 'Method ‘System.Object CompareObjectEqual(System.Object, System.Object, Boolean)’ has no supported translation to SQL. Solution to error'»

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