ตอนที่ 8 : การใช้ IF....ELSE... สร้างเงื่อนไข (MySQL : Stored Procedure)

IF if_expression THEN
   # Statement 1
ELSEIF elseif_expression THEN
   # Statement 2
ELSE
   # Statement 3
END IF;

DROP PROCEDURE IF EXISTS getCustomer;

DELIMITER //
CREATE PROCEDURE getCustomer(IN pType VARCHAR(1))
BEGIN

	IF pType = "1 "THEN
		SELECT A.CUSTOMER_ID, A.NAME, A.EMAIL, B.COUNTRY_NAME FROM customer A 
			LEFT JOIN country B ON  A.COUNTRY_CODE = B.COUNTRY_CODE 
				WHERE A.COUNTRY_CODE = 'TH';
	ELSEIF  pType = "2" THEN
		SELECT A.CUSTOMER_ID, A.NAME, A.EMAIL, B.COUNTRY_NAME FROM customer A 
			LEFT JOIN country B ON  A.COUNTRY_CODE = B.COUNTRY_CODE 
				WHERE A.COUNTRY_CODE = 'US';
	ELSE
		SELECT A.CUSTOMER_ID, A.NAME, A.EMAIL, B.COUNTRY_NAME FROM customer A 
			LEFT JOIN country B ON  A.COUNTRY_CODE = B.COUNTRY_CODE 
				WHERE A.COUNTRY_CODE = 'UK';
	END IF;

END //
DELIMITER ;

CALL getCustomer('2');