In a login system, I want the user to type the "user" or "email" that is contained in the DB.
This works perfectly:
DBRead('usuarios', "WHERE usuario = '$user' OR email ='$user' AND senha = '$password'");
However, I hate repeating code. Is there a more logical way to do this?
Something like:
WHERE usuario or email = '$user'
Whether a field has multiple values or whether a value is in several different values can be used to IN . Here are two examples:
SELECT ... WHERE id IN (1,5,6,9); -- retorna linhas onde o ID é um, cinco, seis ou nove
and to search for a value in more than one field:
SELECT ... WHERE "xis" IN (principal, reserva, outros); -- retorna linhas em que ao menos
-- um dos três campos listados
-- seja a string "xis"
So, in your case:
WHERE '$user' IN ( usuario, email ) AND senha = '$password'
See working on SQL Fiddle .
IN starts to be advantageous in several parameters, for example in IN ( usuario, email, inscricao, cpf ) if one day needs it in some application. The gain in speed / processing is minimal (basically saves transmission and allocation of repeated values), but ease of maintenance and legibility increases a bit.
That's the way it's done. There is no shortcut.
But I suggest delimiting between parentheses to avoid inconsistency:
DBRead('usuarios', "WHERE (usuario = '$user' OR email ='$user') AND senha = '$password'");
Obviously, disregarding the use of VIEW or custom functions.