Parameter Usage

Data will be passed in and out of a stored procedure, even when the purpose of the procedure is not to return information. All variables defined as parameters have to be prefixed with an @ sign. The normal practice is to define input parameters before any output parameters.

As with any column in a database, use the data type that is most appropriate for the parameter and if the parameter has to match with a column in the table, then ensure that both the data types match exactly.

If the parameter does not match a column but will be still used, for example, as a join condition or a filter condition, then use a data type and size appropriate to the type of data, rather than have everything as character data type. Also, wherever possible, use varchar or nvarchar rather than char, just as you will in your inline T-SQL, which will avoid unnecessary spaces being passed across networks.