mysql - PHP branching optimization and efficiency -

i've come across problems numerous times , have had feeling it's not efficient logic , can't seem find straight answer:

in event of needing check database based on criteria, , update record if match true, while moving on different statement if match false, , inserting new record if database matches come false, there more efficient way optimize current branching?

$id = *first query id* //returns null if no match if (is_null($_id)) { #no match   $id = *fallback query looking id *; -->returns null if no match } if (is_null($id)) {#still no match   $id = *last fallback query looking id*; -->returns null if no match }   if (is_null($id)) { # no match found, doesn't exist in db insert     //code insert new record } else { #match found     //code update record* } 

have looked using replace into?

http://www.mysqltutorial.org/mysql-replace.aspx