Question

对于表付款中的每个用户名，我应该分别向payment_amount表 total_balance 中插入total_money的总和，每次自动插入当表 Payments

上插入了新的丝绒时

例如： 用户“ John”用2次100 $和50 $填充了他的帐户，帐户中的总计150 $

表格示例：

表格：付款

 ID      username     payment_amount    Status  
+-------+-------------+-------------+-----------+
|   1   |  John       |     100     | Complete  |
+-------+-------------+-------------+-----------+
|   2   |  John       |     50      | Complete  |
+-------+-------------+-------------+-----------+
|   3   |  Alex       |     100     | Complete  |
+-------+-------------+-------------+-----------+

表格：总余额

 ID      username      total_money      
+-------+-------------+-------------+
|   1   |  John       |     150     | 
+-------+-------------+-------------+
|   2   |  Alex       |     100     |
+-------+-------------+-------------+

此处已回答我的问题，但我无法将触发器配置为适用于上述表格 Here Solved 1-answer

Answer 1

您应该在https://dev.mysql.com/doc/refman/8.0/en/triggers.html上阅读mysql触发器。在这个问题中，触发代码很简单。

drop table if exists t,t1;
create table t(id int auto_increment primary key,name varchar(20),balance int);
create table t1(id int auto_increment primary key, tid int, amount int);
drop trigger if exists t;
delimiter $$
create trigger t after insert on t1
for each row 
begin
    update t
        set balance = ifnull(balance,0) + new.amount
        where t.id = new.tid;
end $$

delimiter ;

insert into t (name) values ('john'),('paul');
insert into t1 (tid,amount) values
(1,10),(1,10),
(2,30);

select * from t1;
+----+------+--------+
| id | tid  | amount |
+----+------+--------+
|  1 |    1 |     10 |
|  2 |    1 |     10 |
|  3 |    2 |     30 |
+----+------+--------+
3 rows in set (0.00 sec)
select * from t;

+----+------+---------+
| id | name | balance |
+----+------+---------+
|  1 | john |      20 |
|  2 | paul |      30 |
+----+------+---------+
2 rows in set (0.00 sec)

请注意使用不平衡余额检查和使用NEW。列（请参见手册）

如何使此触发器适用于我的表？

1 个答案: