Sql – Linq to SQL Class Regeneration

linqlinq-to-sql

I've been using this nifty LINQ to SQL tool for a data access layer in an asp.net project. I keep making changes to the underlying tables and in order for the data classes to recognize the change I have to delete and readd the table which has changed. Is there some shortcut to regenerating the data layer?

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I've run into this same problem and using sqlmetal is definitely a good way to solve it. One approach is to create a batch file that executes your sqlmetal command and that way you can just run the batch anytime you need update your Linq to SQL classes, but what is even slicker solution is to use Visual Studio's Tools->External Tools function to create a command in Visual Studio that runs sqlmetal with your parameters. This works great and you can even drop the created command onto your toolbar for single-click rebuilding.

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.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);

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.net – Entity Framework vs LINQ to SQL

C# – LINQ query on a DataTable

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