You can avoid returning NULL values from your queries by using the IsNULL() function in your T-SQL query or stored procedure, as the code in Listing A shows. This way, if a column contains a NULL, the server substitutes either a string or another specified value (the data types must match). In Listing A's code, for example, I return -1 as a substitute for any NULLs encountered in the Year_Born column data.