LOWER Function

The LOWER function accepts an expression argument and returns a character string in which every uppercase alphabetic character in the expression is replaced by a corresponding lowercase alphabetic character.

The following example shows how to use the LOWER function to perform a case-insensitive search on the City column. This statement directs the database server to replace all instances (that is, any variation) of the words san jose, with the mixed-case format, San Jose.
UPDATE Weather SET City = "San Jose" 
   WHERE LOWER (City) = "san jose";