ELSE               P4

          END

     ELSE CASE

          WHEN P3 >= P4 THEN P3

          ELSE               P4

          END

     END

END

;

   GREATEST function with five parameters

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

VarChar(254), P5 VarChar(254))

 RETURNS VarChar(254)

 LANGUAGE SQL

 SPECIFIC GREATESTOracle5

 DETERMINISTIC

 CONTAINS SQL

 NO EXTERNAL ACTION

 RETURN 

CASE

WHEN P1 >= P2

THEN CASE

     WHEN P1 >= P3

     THEN CASE

          WHEN P1 >= P4

          THEN CASE

               WHEN P1 >= P5 THEN P1

               ELSE               P5

               END 

          ELSE CASE

               WHEN P4 >= P5 THEN P4

               ELSE               P5

               END

          END

     ELSE CASE

          WHEN P3 >= P4

          THEN CASE

               WHEN P3 >= P5 THEN P3

               ELSE               P5

               END

          ELSE CASE

               WHEN P4 >= P5 THEN P4

               ELSE               P5

               END

          END

348 

MySQL to DB2 UDB Conversion Guide