Question

我需要在mySQL表中进行简单的数学运算。

我有桌子payment_tbl 有字段：正常，罚款，退款并试图添加已归档的正常+罚款+退款？

payment_tbl代码：

create table payment_tbl (
payment_id INT (10) PRIMARY KEY AUTO_INCREMENT, 
payment_amount decimal (5,2) not null, 
payment_date DATE not null,
normal decimal (5,2) not null,
penalty decimal (5,2) not null,
refund decimal (5,2) not null,
out decimal (5,2));

INSERT into payment_tbl (
payment_amount, 
payment_date, 
normal, 
penalty,
refund)
values ('5.55', '2015-05-05', '5.55','0', '0');

所以我试图把这个列作为所有三笔付款的总和？

Answer 1

以下是generated columns的文档：

CREATE TABLE payment_tbl(
    payment_id INT (10) PRIMARY KEY AUTO_INCREMENT,
    payment_amount decimal (5,2) not null,
    payment_date DATE not null,
    normal decimal (5,2) not null,
    penalty decimal (5,2) not null,
    refund decimal (5,2) not null,
    `out` decimal (5,2) AS (normal+penalty+refund)
);

我将out列的定义修改为其他3列的总和。你不需要触发器。

Answer 2

您可以使用此查询来添加COLUMN。如果您使用PERSISTENT Query，您还可以在此COLUMN上添加INDEX。

ALTER TABLE payment_tbl
ADD COLUMN `out` DECIMAL(5,2) AS ( normal + penalty + refund)  VIRTUAL;

ALTER TABLE payment_tbl
ADD COLUMN `outp` DECIMAL(5,2) AS ( normal + penalty + refund)  PERSISTENT;

mySQL 5.7 - 计算列/触发器功能

2 个答案: