T-SQL - Return custom error message and end query

Question

I have a lengthy stored procedure in which I would like to do something like the following:

IF @SubPageDirectory IS NULL
BEGIN
    RAISERROR('@SubPageDirectory cannot be NULL', 10, 1)
    EXIT STORED PROCEDURE
END

Basically I wish to check whether my variable is NULL, and if it is, return an error message to my .NET Web Application, and stop running the query at that stage. How can I achieve this?

Answer 1

IF @SubPageDirectory IS NULL 
BEGIN 
    RAISERROR('@SubPageDirectory cannot be NULL', 16, 1) --change to > 10
    RETURN --exit now
END