Do you know a way to make a fastest select statement from a db in mysql.I have to make a select from over 150000 elements in the database and it takes a long time to do it.Is the index useful only for using join?I am using PHP if it helps you with something.
Read the documentation for you DBMS, they will likely have stuff on how to optimize the speed of a query. EXPLAIN (an SQL keyword) may help you as well.