SQL FUNCTION GREATEST.

GREATEST(expr1 [, expr2 ]...)

SQL> COL GREATEST FORMAT 999
SQL> SELECT GREATEST(5,1,4,2) AS GREATEST FROM dual;

GREATEST
--------
       5

SQL>
SQL> SELECT GREATEST(5,1,4,2,'6') AS GREATEST FROM dual;

GREATEST
--------
       6

SQL>
SQL> SELECT GREATEST(5,1,44,2,6) AS GREATEST FROM dual;

GREATEST
--------
      44

SQL>
SQL> COL GREATEST FORMAT A10
SQL> SELECT GREATEST('5','1','4','2',6) AS GREATEST FROM dual;

GREATEST
----------
6

SQL>
SQL> SELECT GREATEST('5','1','44','2','6') AS GREATEST FROM dual;

GREATEST
----------
6

SQL>
SQL> SELECT GREATEST('Daniel','David') AS GREATEST FROM dual;

GREATEST
----------
David

SQL>
SQL> SELECT GREATEST('Daniel',' David') AS GREATEST FROM dual;

GREATEST
----------
Daniel

SQL>