It converts alpha character values to lower case.
The return value has the same data types as argument CHAR type (CHAR or VARCHAR2).

Syntax :  

LOWER(Column/Expression)

Examples :  
1.
SELECT
'ORACLE CORPORATION' String,
LOWER('ORACLE CORPORATION') Lower
FROM DUAL;

2.
SELECT Ename, LOWER('MY INFORMATION') Lower
FROM Emp;

3.
SELECT Ename, LOWER(Ename) Lower
FROM Emp
WHERE Job= 'MANAGER';

4.
SELECT 'The'||Ename||'" s Designation is '|| Job Employee
FROM  Emp
WHERE LOWER(Job)= 'manager';