Question

我需要在插入或删除员工（EMPLOYERS TABLE）时触发，表SHOPS UPDATE中的属性EMPTOTAL。

EMPLOYERS表有一个名为SHOP的字段（和外键），它引用了SHOPS表。

我知道它应该与此类似，但我没有任何涉及我的练习中超过1个表的示例。

CREATE OR REPLACE TRIGGER UPD_EMPTOTAL BEFORE INSERT OR DELETE ON EMPLOYERS FOR EACH ROW
DECLARE
BEGIN
IF INSERTING THEN
UPDATE SHOPS SET EMPTOTAL=EMPTOTAL+1;
ELSIF DELETING THEN
UPDATE SHOPS SET EMPTOTAL=EMPTOTAL-1;
END IF;

END;

（我已尝试过UPDATE句子或为商店声明变量等其他内容，但我不清楚这一点，所以我只是在这里解析了我最确定的代码）。

Answer 1

这可能是让触发器工作所需的全部内容：

create or replace trigger upd_emptotal
   before insert or delete on employers
   for each row
declare
begin
   if inserting
   then
      -- Update only shop total for the shop
      -- in the employer record.
      -- :new.shop is the value being inserted in the table.

      update shops
         set emptotal = emptotal + 1
       where shop = :new.shop;
   elsif deleting
   then
      -- Update only shop total for the shop
      -- in the employer record.
      -- :old.shop is the value in the record being deleted.
      update shops
         set emptotal = emptotal - 1
       where shop = :old.shop;
   end if;

end;

Oracle在插入和删除时触发更新字段（字段+ 1和字段-1）

1 个答案: