從選擇在MySQL

Question

我想從以下SELECT查詢刪除導致的行刪除

select customer_ID, order_ID, t1, t2 
from web_order, items_table as a, items_table as b 
    where (web_order.t1 = a.item_name and a.quantity) 
    and (web_order.t2 = b.item_name and b.quantity) 
    and ((a.quantity < b.quantity)); 

這是我的DELETE查詢

delete from web_order where customer_ID in 
(select customer_ID, order_ID, t1, t2 
from web_order, items_table as a, items_table as b 
    where (web_order.t1 = a.item_name and a.quantity) 
    and (web_order.t2 = b.item_name and b.quantity) 
    and ((a.quantity < b.quantity))); 

但我得到這個錯誤

ERROR 1241 (21000): Operand should contain 1 column(s) 

Answer 1

你不能從刪除語句中刪除的表中選擇 - 這就像試圖添加/刪除它當你迭代它時，從一個集合中獲取ems。

下面是來自MySQL docs官方聲明：

子查詢

你不能從表中刪除，並在 子查詢中從同一個表中選擇。

您將需要使用您的select語句將customer_ID值插入臨時表中，然後從刪除中的臨時表中進行選擇。

所以，它會是這個樣子（我假設CUSTOMER_ID是在你的web_order表中的INT列）：

CREATE TEMPORARY TABLE CustomerIDs (Customer_ID INT NOT NULL) 

INSERT INTO CustomerIDs 
select customer_ID from web_order, items_table as a, items_table as b 
where (web_order.t1 = a.item_name and a.quantity) 
and (web_order.t2 = b.item_name and b.quantity) 
and ((a.quantity < b.quantity)) 

DELETE FROM web_order WHERE Customer_ID IN (SELECT Customer_ID FROM CustomerIDs) 

DROP TABLE CustomerIDs