PostgreSQL 在插入或更新时触发
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PostgreSQL Trigger on Insert or Update
提问by Ozzy
I have two tables. I want to create a trigger on the cartable which will insert or delete on the fueltable depending on a certain value.
我有两张桌子。我想在car表上创建一个触发器，它将fuel根据某个值在表上插入或删除。
Car
车
id - SERIAL
fuel - BOOLEAN
Fuel
燃料
car_id - INTEGER
I am not including any row data as the description of the trigger does not need it.
我不包括任何行数据，因为触发器的描述不需要它。
Basically, I want to create a trigger on the Cartable that:
基本上，我想在Car表上创建一个触发器：
- Runs on an insert or update.
- Inserts
Car.idintoFueltable ifCar.fuel is true. - If
Car.fuel is false, the trigger should delete all rows in theFueltable whereFuel.car_id = Car.id.
- 在插入或更新时运行。
- 如果 ，则插入
Car.id到Fuel表中Car.fuel is true。 - 如果
Car.fuel is false，触发器应该删除Fuel表中的所有行whereFuel.car_id = Car.id。
How would I do this?
我该怎么做？
EDIT: To clarify I am using Postgres
编辑：为了澄清我正在使用 Postgres
采纳答案by Orangecrush
Since you haven't mentioned the RDBMS, I assume it is Oracle. Below is the trigger. If you are using another RDBMS, tweak the code to fit the syntax.
由于您还没有提到 RDBMS，我假设它是 Oracle。下面是触发器。如果您使用另一个 RDBMS，请调整代码以适应语法。
CREATE OR REPLACE TRIGGER TRG_CAR
AFTER INSERT OR UPDATE ON CAR
FOR EACH ROW
BEGIN
IF :new.FUEL THEN
INSERT INTO FUEL (CAR_ID) VALUES (:new.ID);
ELSE
DELETE FROM FUEL WHERE CAR_ID = :new.ID;
END IF;
END;
