September 14, 2005 Ted Holt
In one of my son’s favorite M*A*S*H episodes, a certain Captain Tuttle is given accolades for his bravery and humanitarianism. What gives the show its humor is that Captain Tuttle does not exist. I would like to share some interesting facts about the relational database’s counterpart to Captain Tuttle–the null value. I have found, as did Hawkeye Pierce and the gang, that non-existent things can be useful.
1. Null indicates that a field has no value. A field with a null value is not equivalent to an alpha field with blanks or a numeric field with zeros. Such fields have