title: how to check a parameter is null or empty in mysql?
body: <p>How can I check if a parameter is null or empty in a stored procedure in mysql?
  In other words what is equivalent of <code>ISNULL</code>in mysql ?
  I tried <code>IFNULL</code> and <code>IS NULL</code>but they didn't work. </p>
  
  <p>What I want is, to check if a parameter of stored procedure is null or empty then procedure raises an error and doesn't insert new record into table.</p>