title: Tuple "not in" clause to run in mysql and mssql issue
body: <p>I'm trying to get data from a table containing some where clauses using a query that runs both on MySQL and SQL Server.
  That query contains a tuple clause validation from the joined data not to exist in a subquery out of a different table.
  This query runs ok in MySQL but not in SQL Server. Tried &quot;NOT EXISTS&quot; without success...</p>
  <pre><code>SELECT
      a.col1,
      b.col2
  FROM
      tableA a
      JOIN tableB b ON b.col_x = a.col_x
      WHERE a.col5 IN ('VAL1', 'VAL2', 'VAL3')
      AND (a.col2, b.col4) NOT IN (
          SELECT
              c.col2,
              c.col4
          from
              tableC c
      )
  </code></pre>
  <p>Running in SQL Server I get</p>
  <blockquote>
  <p>An expression of non-boolean type specified in a context where a condition is expected, near ','.</p>
  </blockquote>
  <p>In the &quot;NOT IN / NOT EXISTS&quot; part of the SQL and clause. Any ideas?</p>