My question is why couldn't you rewrite the example in the article as the following:

IF @Last <> '' AND @First = ''

BEGIN

SELECT * FROM authors WHERE au_lname LIKE @Last + '%'

END

ELSE IF @First <> '' AND @Last = ''

BEGIN

SELECT * FROM authors WHERE au_fname LIKE @First + '%'

END

ELSE

BEGIN

SELECT * FROM authors WHERE au_lname LIKE @Last + '%' AND au_fname LIKE @First + '%'

END

What is the advantage here of having 3 separate stored procedures? Forgive my ignorance.