title: Database Index not used if the where criteria is !=?
body: <p>I have a index on a column and it is correctly used when the query is </p>
  
  <pre><code>select * from Table where x = 'somestring'
  </code></pre>
  
  <p>However it seems to be not used when the query is something like</p>
  
  <pre><code>select * from Table where x != 'someotherstring'
  </code></pre>
  
  <p>Is this normal or am I missing something else in the query? The actual query is of course much larger and so it could be caused by some other factor. Any other ideas why an index would not be used in a query?</p>