MySQL 存储过程CASE语句用法

CASE语句有两种形式：简单的搜索CASE语句。下面讲讲MySQL 存储过程CASE语句用法。

1，CASE语法结构

     CASE  case_expression
    WHEN when_expression_1 THEN commands
   WHEN when_expression_2 THEN commands
    ...
    ELSE commands
   END CASE;

2，CASE应用实例

   DELIMITER $$

CREATE PROCEDURE GetCustomerShipping(
in p_customerNumber int(11),
out p_shiping varchar(50))
BEGIN
DECLARE customerCountry varchar(50);

SELECT country INTO customerCountry

FROM customers
WHERE customerNumber = p_customerNumber;

CASE customerCountry

WHEN ‘USA‘ THEN
SET p_shiping = ‘2-day Shipping‘;
WHEN ‘Canada‘ THEN
SET p_shiping = ‘3-day Shipping‘;
ELSE
SET p_shiping = ‘5-day Shipping‘;
END CASE;

END$$

如果WHEN子句中的when_expression与case_expression的值匹配，则ELSE子句中的命令将被执行。ELSE子句是可选的。 如果省略ELSE子句，并且找不到匹配项，MySQL将引发错误。

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MySQL 存储过程CASE语句用法

原文：http://blog.51cto.com/13959155/2293785