CREATE TABLE JAN07
      (
        COL1 VARCHAR2(50),
        COL2 VARCHAR2(50),
        COL3 VARCHAR2(50)
      )

      INSERT ALL
      INTO JAN07 VALUES ('100A','{XXX}','888')      
      INTO JAN07 VALUES ('ZZZ','ZZC}','00C')
      INTO JAN07 VALUES ('TRUE','ABJ','TRUE')
      SELECT * FROM DUAL;

CASE SUBSTR(PARAM1, -1)
		WHEN '{' THEN REPLACE(PARAM1, '{', '0')
		WHEN 'A' THEN REPLACE(PARAM1, 'A', '1')
		WHEN 'B' THEN REPLACE(PARAM1, 'B', '2')
		WHEN 'C' THEN REPLACE(PARAM1, 'C', '3')
		WHEN '}' THEN '-' || REPLACE(PARAM1, '}', '0')
		WHEN 'J' THEN '-' || REPLACE(PARAM1, 'J', '1')
		WHEN 'K' THEN '-' || REPLACE(PARAM1, 'K', '2')
	      ELSE
		PARAM1

 
CREATE OR REPLACE FUNCTION rep_string (param1 IN varchar2)
   RETURN VARCHAR2 IS
   BEGIN
        RETURN 
                CASE SUBSTR(PARAM1, -1)
		                  WHEN '{' THEN REPLACE(PARAM1, '{', '0')
		                  WHEN 'A' THEN REPLACE(PARAM1, 'A', '1')
		                  WHEN 'B' THEN REPLACE(PARAM1, 'B', '2')
		                  WHEN 'C' THEN REPLACE(PARAM1, 'C', '3')
		                  WHEN '}' THEN '-' || REPLACE(PARAM1, '}', '0')
		                  WHEN 'J' THEN '-' || REPLACE(PARAM1, 'J', '1')
		                  WHEN 'K' THEN '-' || REPLACE(PARAM1, 'K', '2')
	             ELSE
		                  PARAM1
               END;
    END;
    /

SQL> select rep_string('COL1') from dual;

REP_STRING('COL1')
--------------------------------------------------------------------------------
COL1

select rep_string(COL1) from jan07
1001
ZZZ
TRUE