title: Does MySQL have an aggregate ST_UNION()?
body: <p>I'm struggling for hours to get my query work but with no success.</p>
  <p>I have a table with a GEOMETRY column which stores the POLYGON of a given area from sub-localities.
  Now i want to Union them all to one higher level boundary of the parent area for example:</p>
  <pre><code>SELECT ST_Union(geometry) FROM area
  </code></pre>
  <p>I always the the error:</p>
  <blockquote>
  <p>#1582 - Incorrect parameter count in the call to native function 'ST_Union'</p>
  </blockquote>
  <p>I don't think that this is the wanted behaviour of the function, since this makes it completely worthless. Does anybody know how to use this function to generate the intended results?</p>