lower Function
The lower function converts all the characters in a string to lowercase.
Syntax
returnvalue lower (source)
source ::= any*
returnvalue ::= stringSemantics
- source
- 
                        The input string that should be converted to lowercase. This argument is implicitly cast to a sequence of strings. 
- returnvalue
- 
                        Returns NULL if the source argument is NULL. Returns NULL if the source argument is an empty sequence or a sequence with more than one item. 
Note:
If you want to convert a sequence with more than one item, see the Sequence Transform Expressions section.Example 12-53 lower Function
In this example, the lastname field is converted to lowercase.
SELECT id, firstname, lower(lastname) FROM users +----+-----------+----------+
 | id | firstname | Column_3 |
 +----+-----------+----------+
 | 10 | John      | smith    |
 | 20 | Mary      | ann      |
 | 30 | Peter     | paul     |
 +----+-----------+----------+