LANGUAGE SQL

 SPECIFIC GREATESTOracle3

 DETERMINISTIC

 CONTAINS SQL

 NO EXTERNAL ACTION

 RETURN 

CASE

WHEN P1 >= P2

THEN CASE

     WHEN P1 >= P3 THEN P1

     ELSE               P3

     END

ELSE CASE

     WHEN P2 >= P3 THEN P2

     ELSE               P3

     END

END

;

   GREATEST function with four parameters

CREATE FUNCTION GREATEST (P1 VarChar(254), P2 VarChar(254), P3 VarChar(254), P4 

VarChar(254))

 RETURNS VarChar(254)

 LANGUAGE SQL

 SPECIFIC GREATESTOracle4

 DETERMINISTIC

 CONTAINS SQL

 NO EXTERNAL ACTION

 RETURN 

CASE

WHEN P1 >= P2

THEN CASE

     WHEN P1 >= P3

     THEN CASE

          WHEN P1 >= P4 THEN P1

          ELSE               P4

          END

     ELSE CASE

          WHEN P3 >= P4 THEN P3

          ELSE               P4

          END

     END

ELSE CASE

     WHEN P2 >= P3

     THEN CASE

          WHEN P2 >= P4 THEN P2

 Appendix A. Sample code for user defined functions 

347