Oracle/PLSQL: AFTER DELETE Trigger

 

Oracle/PLSQL: AFTER DELETE Trigger

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An AFTER DELETE Trigger means that Oracle will fire this trigger after the DELETE operation is executed.

译：AFTER DELETE表示在DELETE操作执行后，ORACLE会引发该触发器

The syntax for an AFTER DELETE Trigger is:

译：AFTER DELETE触发器的语法如下：

CREATE or REPLACE TRIGGER trigger_name
AFTER DELETE
    ON table_name
    [ FOR EACH ROW ]
DECLARE
    -- variable declarations
BEGIN
    -- trigger code
EXCEPTION
    WHEN ...
    -- exception handling
END;

trigger_name is the name of the trigger to create.

译：trigger_name表示创建的触发器名

Restrictions:

·   You can not create an AFTER trigger on a view.

·   You can not update the :NEW values.

·   You can not update the :OLD values.

译：

限制：

·   不能够在视图上创建AFTER触发器。

·   不能够更新 :NEW 的值。

·   不能够更新 :OLD 的值。

For example:

If you had a table created as follows:

译：如果你有一个如下的表：

CREATE TABLE orders

(

order_id

number(5),

 

quantity

number(4),

 

cost_per_item

number(6,2),

 

total_cost

number(8,2)

);

We could then create an DELETE UPDATE trigger as follows:

译：我们像下面这样创建一个DELETE UPDATE触发器：

CREATE OR REPLACE TRIGGER orders_after_delete
AFTER DELETE
    ON orders
    FOR EACH ROW

DECLARE
    v_username varchar2(10);

BEGIN

    -- Find username of person performing the DELETE on the table
    SELECT user INTO v_username
    FROM dual;

    -- Insert record into audit table
    INSERT INTO orders_audit
     ( order_id,
       quantity,
       cost_per_item,
       total_cost,
       delete_date,
       deleted_by)
    VALUES
     ( :old.order_id,
       :old.quantity,
       :old.cost_per_item,
       :old.total_cost,
       sysdate,
       v_username );

END;