mysql_存储过程

创建存储过程

创建一个简单的存储过程

CREATE PROCEDURE mypro()
BEGIN
SELECT * FROM products;
END;

调用存储过程

CALL mypro()

删除存储过程

DROP PROCEDURE IF EXISTS mypro

下面。创建带参数的存储过程，just like function

CREATE PROCEDURE newpro(
    OUT min DECIMAL(8,2),
    OUT avg DECIMAL(8,2),
    OUT max DECIMAL(8,2)
)
BEGIN
    SELECT MIN(item_price) INTO min FROM orderitems;
SELECT avg(item_price) INTO avg FROM orderitems;
SELECT max(item_price) INTO max FROM orderitems;

END;

调用

CALL newpro(@最小,@平均,@最大);
SELECT @最小,@平均,@最大;

得到

-----------------------------------------

带参数in的存储过程

CREATE PROCEDURE newproin(
    IN pro_id int,
    OUT min DECIMAL(8,2),
    OUT avg DECIMAL(8,2),
    OUT max DECIMAL(8,2)
)
BEGIN    
    SELECT MIN(item_price) FROM orderitems WHERE orderitems.order_item=pro_id INTO min;
    SELECT avg(item_price) FROM orderitems WHERE orderitems.order_item=pro_id INTO avg ;
    SELECT max(item_price) FROM orderitems WHERE orderitems.order_item=pro_id INTO max;
END;

调用过程

CALL newproin(4,@最小,@平均,@最大);
SELECT @最小,@平均,@最大;

--------------------------------------------

过程中间再复杂点

CREATE PROCEDURE propro(
    IN pro_id int,--传递进来的商品id
    IN flag boolean,--是否需要加税
    OUT pricetotal DECIMAL(8,2)--返回出去的值
)
BEGIN    
    DECLARE temprice DECIMAL(8,2);--函数内部变量
    DECLARE rate int DEFAULT 7;--内部变量税率，千分之七

    SELECT SUM(item_price)FROM orderitems WHERE orderitems.order_item=pro_id INTO temprice;--总价into到内部变量中
    IF flag THEN--判断是否加税
        SELECT temprice+(temprice*(rate*0.001)) INTO temprice;
    END IF;
    SELECT temprice INTO pricetotal;--内部变量into到返回出去的变量中
END;

调用依然很简单

CALL propro(3,FALSE,@totalprice);
SELECT @totalprice;