Question

I have a system that generates a batch of random codes up to 100 at a time. They are then inserted in to a database. I am using a code generator and it would be pretty unlikely a similar code could be created again but to make sure I want to check the DB for a duplicate anyway. My theory..

  $amount_of_codes


  while ($x != $amount_of_codes)
    {
    $code = gencode();
    $mysql_check = "SELECT code FROM data WHERE code = '$code'";
    $mysql_check_result = mysql_query($mysql_check);
    $check = mysql_num_rows($mysql_check_result);
     if (!$check)
      {
      mysql_query("INSERT INTO data(code) values('$code')")
      $x++
      } 
    }

seems messy, any better ideas?

Answer 1

Give the Code Column a UNIQUE constraint:

CREATE TABLE Code
(
  Code ..
..
  CONSTRAINT Code_Unique UNIQUE (Code),
..
);

When inserting you only need to capture database exceptions/errors, not worrying if a Code already exists.