MySql 存储过程

2017-03-07  本文已影响9人  zshanjun

考虑有这样一个情景。你需要获得与以前一样的订单合计,但需要对合计增加营业税,不过只针对某些客户。可以使用存储过程来实现这个功能

-- Name: ordertotal
-- Parameters: onumber = order number
--         taxable = 0 if not taxable, 1 if taxable
--         ototal  = order total variable

create procedure ordertotal(
     in onumber int,
    in taxable boolean,
    out ototal decimal(8,2)
) comment 'obtain order total, optionally adding tax'
begin

-- declare variable for total
declare total decimal(8,2);
-- declare tax percentage
declare taxrate int default 6;

-- get the order total
select sum(item_price * quantity)
from orderitems
where order_num = onumber
into total;

-- Is this taxable?
if taxable then
   -- yes, so add taxrate to the total
   select total + (total / 100 * taxrate) into total;
end if;

-- finally, save to our variable
select total into ototal;

end;


//使用
//所有mysql变量都必须以@开始
call ordertotal(20005, 0 @total);
select @total;

//结果
+--------+
| @total |
+--------+
| 149.87 |
+--------+

call ordertotal(20005, 1 @total);
select @total;

//结果
+--------+
| @total |
+--------+
| 158.86 |
+--------+


----
//注意,以上代码如果直接敲入到命令行会有问题,因为存储过程里面有";"结束标识,会导致存储过程无法正确运行
//因此,在创建存储过程前,可以临时更改结束标识

delimiter //

//注意除"\"外,其它字符都可以作为结束标识
//当创建存储过程后,再改结束标识为";"即可

---
使用drop procedure ordertotal;删除存储过程

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