Contents Index Using views with Transact-SQL outer joins Specialized joins

ASA SQL User's Guide
  Joins: Retrieving Data from Several Tables
    Inner and outer joins
      Transact-SQL outer joins (*= or =*)

How NULL affects Transact-SQL joins

NULL values in tables or views being joined never match each other in a Transact-SQL outer join. The result of comparing a NULL value with any other NULL value is FALSE.


Contents Index Using views with Transact-SQL outer joins Specialized joins