title: distinct in sql
body: <p>This is my SQL:</p>
  
  <pre><code>SELECT DISTINCT(CASE WHEN state=18 THEN lga ELSE 'Others' END) LGA,
      COUNT(CASE WHEN choice=21 THEN choice END ) NDCH
  FROM bio   
  GROUP BY lga
  </code></pre>
  
  <p>My expectation is for it to give me all LGA with state=18, and if the state is not equal to 18 let them be grouped as 'Others', but I usually have more than one 'Others'.
  Please help.</p>