17.10 - Example: Searching a Table That Might Contain Nulls - Advanced SQL Engine - Teradata Database

Teradata Vantageā„¢ - SQL Functions, Expressions, and Predicates

Advanced SQL Engine
Teradata Database
Release Number
Release Date
July 2021
Content Type
Programming Reference
Publication ID
English (United States)

You must be careful when searching a table that might contain nulls. For example, if the EdLev column contains nulls and you submit the following query, the result contains only the names of employees with an education level of less than 16 years.

   SELECT Name, EdLev 
   FROM Employee 
   WHERE (EdLev < 16) ;

To ensure that the result of a statement contains nulls, you must structure it as follows.

   SELECT Name, EdLev 
   FROM Employee 
   WHERE (EdLev < 16) 
   OR (EdLev IS NULL) ;