ตอนที่ 16 : การสร้าง Function บน Oracle Database (Oracle : Function)

CREATE OR REPLACE FUNCTION function_name RETURN data_type
AS 
BEGIN
  RETURN ;
END FUNCTION_NAME ;

CREATE OR REPLACE FUNCTION DIFF_AMOUNT(pAmount1 DECIMAL, pAmount2 DECIMAL) 
  RETURN DECIMAL 
AS 
  diffAmount DECIMAL(18,2) DEFAULT '0';
BEGIN
  diffAmount := pAmount1 - pAmount2;
  RETURN diffAmount;
END DIFF_AMOUNT;

SELECT DIFF_AMOUNT(2000, 500) As TOTAL_DIFF FROM DUAL;

SELECT T.*,DIFF_AMOUNT(BUDGET, USED) AS TOTAL_DIFF FROM CUSTOMER T;