是否可以使用LINQ从存储过程中返回返回值和结果集

Question

Looking for suggestions on cleanest way to get the return value and the result set (without passing a referenced parameter to the stored proc).

MY stored procs have return values to show errors, etc and they end with a select statement to get the information. With regular commands I would create an output parameter which would hold the return value. I can't change the stored procs in the db so I can't pass a different output parameter other then the return value.

thoughts??

Answer 1

When you create a stored procedure in the LINQ to SQL Data Context designer by dragging it from the Server Explorer, the designer will analyze the sproc to determine if it returns a result set. Unless it features heavy dynamic SQL, it's usually spot on.

If it does, the method generated returns ISingleResult<T> where T is either a class generated from an analysis of your sproc to fit the shape of the result set, or one you specify in the sproc properties page. Because ISingleResult derives from IEnumerable , most people do a simple foreach on the result to get their result set. But what most people forget is that ISingleResult also derives from IFunctionResult , which has a property called ReturnValue . This is the return value from the sproc.

So all you have to do is something along the lines of:

using(var dc = new MyDataContext())
{
    var results = dc.MyStoredProcedure();
    var returnValue = (int)results.ReturnValue; // note that ReturnValue is of type object and must be cast.
    foreach(var row in results)
    {
        // process row
    }
}