Use of Comparison Operators with Strings : Operators « PL SQL Operators « Oracle PL/SQL Tutorial

When using character strings in comparison expressions, the result depends on several things:

1. Character set
2. Datatype
3. Case (upper versus lower)

In the typical ASCII environment,

1. all lowercase letters are actually greater than all uppercase letters,
2. digits are less than all letters, and
3. the other characters fall in various places depending on their corresponding ASCII codes.