How I can use a range between 0-20 on this sql query?

Question

How I can use a range between 0-20 on this sql query?

  $sql = 'SELECT * FROM t1
          LEFT JOIN t2 ON t2.wid = t1.wid  
          UNION
          SELECT * FROM t1
          RIGHT JOIN t2 ON t2.wid = t1.wid
          limit 0, 20';
  $result = db_query($sql);//->fetchField();

Answer 1

Pass LIMIT into your query. and your limit would be variable every time like

$sql = 'SELECT * FROM (SELECT * FROM t1
          LEFT JOIN t2 ON t2.wid = t1.wid  
          UNION
          SELECT * FROM t1
          RIGHT JOIN t2 ON t2.wid = t1.wid) AS A LIMIT'.$start.','.$end