Question

有一个名为'Coach'的MySQL表，它具有以下属性。

coach_ID int
mileage_of_last_service_date double
mileage double
isAvailable boolean

对于所有行，

isAvailable最初设置为1。我想设置一个触发器来执行以下操作。当里程属性发生更新并且里程数大于100000时，触发器必须为同一个表中的特定属性设置属性，如下所示。

isAvailable = 0
mileage_of_last_service_date = mileage_of_last_service_date + mileage
mileage = 0

这是我写过的查询。

create trigger set_availability_coach after update on coach 
for each row
when old.mileage > 10000 
begin 
update coach
set isAvailable = 0, mileage_of_last_service_date = mileage_of_last_service_date + old.mileage, mileage = 0
where coach.coach_ID = old.coach_ID;
end;

当我运行这个时，我在第3行遇到语法错误。有没有解决这个问题？或者任何其他方式来实现此功能？

Answer 1

我改编了这个，这应该没问题

CREATE TRIGGER set_availability_coach BEFORE UPDATE ON coach 
FOR EACH ROW BEGIN
  IF OLD.mileage > 10000 THEN
    SET NEW.isAvailable = 0,
        NEW.mileage_of_last_service_date = OLD.mileage_of_last_service_date + NEW.mileage,
        NEW.mileage = 0;
  END IF;
END

Answer 2

您只能在OLD - 触发器see MySQL docs访问BEFORE。如果您不需要UPDATE ... SET ...查询，则可以创建BEFORE UPDATE触发器，并在适当的位置修改NEW字段。

触发更新Mysql中表的属性

2 个答案: