title: How does SQL Server evaluate logical expressions?
body: <p>I am writing a bit complex sql query which - I am afraid - can be heavy to execute. So I'd like to know how MS SQL Server works out some things.</p>
  
  <p>If there is logical expression like ex1 AND ex2, does server always evaluate both of them ? Does it always evaluate ex1 first, and then ex2 (if needed) ?
  Is it specified, and can I rely on that ?</p>