Question

I have two same procedures in two DB, by same I mean:

• Same name
• Same parameters name & type
• End with a select returning same columns types & names (If I put a SELECT ... INTO table it generates the exactly same table).

The only thing which differs is the code building the sql query for the final select.
If I use EF on Database 1 it works as intended, but if I run the code on Database 2 it ends on error:

The data reader is incompatible with the specified ‘Ctx.Procedure_Result’. A member of the type, ‘FooId’, does not have a corresponding column in the data reader with the same name.

I’m using:

• Entity Framework 4.2
• Visual Studio 2010
• Sql Server 2008 R2

I don’t have enough knowledge of EF internals to understand why this is happening.
My idea is that there must be some columns types/names sniffing mecanism which doesn’t sniff the same stuff.

Edit 1:

The procedure doesn’t “return” a table type it just “select” some rows.
This select result is mapped to a ComplexType in the EDMX.

Feel free to ask for more details.

Answer 1

My fault, as suggested I traced the EF queries with SQL Server Profiler.

In fact EF was using NULL in an optional parameter which destroyed the sql query inside the procedure (‘select … ‘ + NULL => NULL).

With a NULL query the procedure select no column at all and it crashes the EF data reader.