mysql - Using functions in WHERE clause -

mysql - Using functions in WHERE clause -

is there, generally, difference between where fieldoftable1 >= 5.54 , where fieldoftable1 >= fieldoftable2 * otherfieldfromtable1 in bring together clause in mysql?

i heard mysql not employ indexes sec case, if both fields indexed, , uses in first case. so, first query executed faster ceteris paribus. true?

upd explain shows mysql uses indexes sec query.

mysql performance indexing