Oracle - Trigger

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CREATE OR REPLACE TRIGGER TRI_DEL_BOOK AFTER DELETE ON BOOKS
FOR EACH ROW
BEGIN
    IF DELETING THEN DELETE FROM BORROW WHERE ID = :OLD.ID;
    END IF;
END;
/

CREATE OR REPLACE TRIGGER TRI_UPD_BOOK AFTER UPDATE ON BOOKS
FOR EACH ROW
BEGIN
    IF UPDATING THEN UPDATE BORROW SET ID = :NEW.ID WHERE ID = :OLD.ID;
    END IF;
END;
/

CREATE OR REPLACE TRIGGER TRI_INS_BOOK AFTER INSERT ON BOOKS
FOR EACH ROW
BEGIN
    /*该部分仅做测试使用*/
    IF INSERTING THEN 
        INSERT INTO BORROW VALUES('109',:NEW.ID,TO_DATE('2019-04-15','YYYY-MM-DD'),:NEW.NAME);
        END IF;
END;
/

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[ Attention ]

：OLD.COLUMN_NAME           --（旧数据表，更新、删除值赋予前的表）

：NEW.COLUMN_NAME          --（在操作insert、update等操作中，在触发器外部被赋予的新值）