But wouldn't this always compare all variables, though? In the syntax with OR, the query engine can see that a variable is empty, thereby satisfying one side of the OR condition, and need not even look in the database.
I am not sure that this is true. This isn't .NET where code branches based on one side of an IF or SWITCH. From what I have seen, the query engine runs both sides and then compares.
But thats just me.