1,if 结构
          IF expression THEN 
         statements;
    END IF;
            IF expression THENstatements;
ELSE
else-statements;
END IF;
IF expression THEN
statements;
ELSEIF elseif-expression THEN
elseif-statements;
ELSE
else-statements;
END IF;
    2,if实例
    DELIMITER $$CREATE PROCEDURE GetCustomerLevel(
in  p_customerNumber int(11), 
out p_customerLevel  varchar(10))
BEGIN
DECLARE creditlim double;
SELECT creditlimit INTO creditlim
FROM customers
WHERE customerNumber = p_customerNumber;
IF creditlim > 50000 THENSET p_customerLevel = ‘PLATINUM‘;
ELSEIF (creditlim <= 50000 AND creditlim >= 10000) THEN
SET p_customerLevel = ‘GOLD‘;
ELSEIF creditlim < 10000 THEN
SET p_customerLevel = ‘SILVER‘;
END IF;
END$$
if用在存储过程中,多多实际实践,增加动手能力
文章来自 www.dc3688.com
原文:http://blog.51cto.com/13959155/2292206