title: Duplicate entry for key 'group_key'
body: <p>I'm running a query in MySQL where I'm grouping by four columns and selecting a lot of things, including the four values I'm grouping by. But I get this error when I run the query:</p>
  
  <pre><code>Duplicate entry '92-0-10-7' for key 'group_key'
  </code></pre>
  
  <p>The 92, 0, 10, and 7 are all values of the four grouped-by columns for a particular row (actually, I checked, and there are 63 rows that fit those parameters). But I have no idea what that means, or how to run my query properly.</p>
  
  <p>My query:</p>
  
  <pre><code>Create table table2 as
  Select round(x, 0) as x, round(a, 0) as a, round(b, 0) as b, c, d, e, f
  from table1
  group by round(x, 0), round(a, 0), round(b, 0), c
  </code></pre>
  
  <p>The 92 would fit x, the 0 a, the 10 b, and the 7 c.</p>
  
  <p>I have no indices on this table.</p>
  
  <p>Thanks!</p>