Although an interesting technique, from a database performance point of view, this is not a very good idea. SARGs are turned into non-SARGs, so indexes won't be used (for an example, rewrite

SELECT * FROM authors WHERE au_lname LIKE 'm%' AND state = 'CA'

in the pubs database with conditional statements in the WHERE clause and compare the execution plans. You will see that the query above uses an index, the query with conditional statements in the WHERE clause does not.