title: Help understanding a SQL statement
body: <p>I have difficulty understanding <code>SELECT * FROM myTable WHERE 0 = ...</code> in the following SQL statement.</p>
  
  <pre><code>SELECT * FROM myTable WHERE 0 = (SELECT COUNT(*) FROM incTable 
  WHERE myTable.export_date &lt;= incTable.export_date 
  AND myTable.colA = incTable.colA 
  AND myTable.colB = incTable.colB 
  AND myTable.colC = incTable.colC)
  </code></pre>
  
  <p>From my understanding, usually in the <code>WHERE</code> clause, a column is evaluated against some other entity (i.e. another column or value). What does it mean to be evaluating against two numbers (i.e <code>WHERE 0 = 5</code>)? Will <code>SELECT * FROM myTable</code> always return the contents of <code>myTable</code> regardless of what the outcome of the <code>WHERE</code> clause in the above SQL statement?   </p>