title: update Informix table with joins
body: <p>Is this the correct syntax for an Informix update?</p>
  
  <pre><code>update table1
  set table1.code = 100
  from table1 a, table2 b, table3 c
  where a.key = c.key
  a.no = b.no
  a.key = c.key
  a.code = 10
  b.tor = 'THE'
  a.group = 4183
  a.no in ('1111','1331','1345')
  </code></pre>
  
  <p>I get the generic -201 'A syntax error has occurred' message, but I can't see what's wrong.</p>