Use the Greatest functions : GREATEST « Miscellaneous Functions « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Miscellaneous Functions
3. GREATEST

SQL>
SQL>
SQL> SET SERVEROUTPUT ON
SQL> DECLARE
  2     v_char VARCHAR2(10);
  3     v_number NUMBER(10);
  4  BEGIN
  5
  6     v_char := GREATEST('A', 'B', 'C');
  7     v_number := GREATEST(1,2,3);
  8
  9     DBMS_OUTPUT.PUT_LINE('Greatest Character: '||v_char);
 10     DBMS_OUTPUT.PUT_LINE('Greatest Number: '||v_number);
 11
 12
 13  END;
 14  /
Greatest Character: C
Greatest Number: 3

PL/SQL procedure successfully completed.

SQL>
SQL>