Question

我有三个表，购买（purchase_id，quantity_purchased，purchase_date，purchase_time，payment_method）库存（inventory_id，amount，item_id）和商品（item_name，price，notes，item_id）我需要创建一个触发器来更新库存（每次进行新购买时，金额 - 数量 - 购买量。这就是我到目前为止所做的：

CREATE TRIGGER inventory_update
AFTER INSERT ON purchases
FOR EACH ROW
UPDATE inventory
SET amount = amount - NEW.quantity_purchased
WHERE purchase_id = NEW.purchase_id;

感谢任何帮助，谢谢

Answer 1

是否有将您的购买表与您的广告资源相关联的外键？

以下是我的头脑风暴，如果您可以确定在插入产品表时销售的产品，它应该可以使用。

Create trigger inventory_update on Dbo.purchases
after insert
as 
declare  @inserted int, @stock int, @pid int
select @Pid= pid from inserted
select @inserted = quantity_purchased from inserted
select @stock = quantity_purchased from dbo.inventory 
where @PID= inventory. inventory_id -- This line needs a way to find out what the purchase item is

if @inserted>@stock
begin
print('Not enough Stock')
rollback
end
Else if @inserted<@stock and @PID is not null
begin
update inventory
set amount= inventory.amount-@inserted
where @PID =inventory.item_ID     -- Once again the issue is figuring out what your purchase item is on this line.
print('A Sale has been made')
end
else
print('There is an error in the process')

Answer 2

我猜我purchases表有一个item_id。如果是这样的话：

DELIMITER $$
CREATE TRIGGER inventory_update AFTER INSERT ON purchases
FOR EACH ROW
BEGIN
    UPDATE inventory i
        SET i.amount = i.amount - NEW.quantity_purchased
        WHERE i.item_id = NEW.item_id;
END;
$$
DELIMITER ;

MySQL尝试创建触发器以在新购买时更新库存

2 个答案: