title: UNION with different data types in db2 server
body: <p>I have built a query which contains UNION ALL, but the two parts of it 
  have not the same data type. I mean, i have to display one column but the 
  format of the two columns, from where i get the data have differences.
  So, if i get an example :</p>
  
  <pre><code>select a,b
  from c
  union all
  select d,b
  from e
  </code></pre>
  
  <p>a and d are numbers, but they have different format. It means that a's length is 15
  and b's length is 13. There are no digits after the floating point.
  Using digits, varchar, integer and decimal didn't work.
  I always get the message : <strong>Data conversion or data mapping error</strong>.
  How can i convert these fields in the same format?</p>