如何修复我的“指定演员表无效”错误？

Question

I'm trying to get the id that is a SMALLINT using OUTPUT on an insert statement and using DataContext.ExecuteQuery (or whatever DataContext method would be more appropriate).

Attempt:

            string query = $@"
                DELETE FROM MyTable WHERE [Name] = '{name}'
                INSERT INTO MyTable ([Name], ...)
                OUTPUT INSERTED.ID
                VALUES ('{name}', ...)";
            short id = (short)context.ExecuteQuery<int>(query).Single();

and I get the error

System.InvalidCastException was unhandled by user code
  HResult=-2147467262
  Message=Specified cast is not valid.
  Source=System.Data
  StackTrace:
       at System.Data.SqlClient.SqlBuffer.get_Int32()
       at System.Data.SqlClient.SqlDataReader.GetInt32(Int32 i)
       at Read_Int32(ObjectMaterializer`1 )
       at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader`2.MoveNext()
       at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source)

I tried using SCOPE_IDENTITY() and same thing happened.

Answer 1

remove the

OUTPUT INSERTED.ID

and add

; Select SCOPE_IDENTITY()

to the end, inside the quotes

ExecuteQuery expects a value to be returned in the result set which is different from an output variable. The InvalidCastException comes from trying to convert the result set (which is null) to an int.

Answer 2

Try:

short id = context.ExecuteQuery<short>(query).Single();

That CAST exception is happening in the code when it's expecting SQL Server to return an Int32 and getting an Int16.