Parameter Markers

Parameter markers, including parameter markers for stored procedures, are specified in the .NET data provider by using the "?" symbol in SQL statements.

UPDATE emp SET job = ?, sal = ? WHERE empno = ? 

Because parameters are not named, the bindings must occur in the order of the parameters in the statement. This means that the calls to the Add() method on the ParameterCollection object (adding the Parameter objects to the collection) must occur in the order of the "?"s in the statement. The name passed to the Add() method does not need to match anything in the SQL statement.