title: Can someone explain to me how this statement is an exclude?
body: <p>Can someone tell me how this is an exclude? </p>
  
  <p>Assuming that tableID is auto generated and in columnY there can be value of 0 or 1. This statement should exclude everything were columnY has a value of 1. </p>
  
  <pre><code>SELECT *
       FROM [table].[dbo].[one] AS t1
  LEFT JOIN [table].[dbo].[one] AS t2
       ON (t1.ColumnX = t2.ColumnX AND columnY = 1)
  WHERE t1.tableID IS NULL
  </code></pre>
  
  <p>So the table would look something like this:</p>
  
  <pre><code>ID   |   ColumnX   | ColumnY
  1        Blue        0
  2        Blue        1
  3        Red         0 
  4        Red         0
  5        Red         1
  </code></pre>