title: SQL GROUP_CONCAT alias in WHERE
body: <p>Here's my sql statement:</p>
  
  <pre><code>SELECT 
      tA.a1, GROUP_CONCAT(tB.b2) AS b2
  FROM
      tableA tA
          LEFT JOIN
      tableB tB ON tA.a2 = tB.b1
  WHERE
      CONCAT(tA.a1, b2) LIKE '%somestring%'
  GROUP BY tA.a1;
  </code></pre>
  
  <p>I get an sql error saying something along the lines of "unknown column name b2 in WHERE".</p>