Question

如果我有这三个表（只是一个例子来学习UNION，这些不是真正的表）：

包含列的表格

Customer: 
id | name        | order_status

Order_Web:
id | customer_id | order_filled

Order:
id | customer_id | order_filled

我希望在Order_Web表或使用Union的客户的Order表中填写订单时更新Customer表中的order_status：

UPDATE c
SET c.order_status = 1
FROM Customer AS c
INNER JOIN Order_Web As ow
      ON c.id = ow.customer_id
WHERE ow.order_filled = 1

UPDATE c
SET c.order_status = 1
FROM Customer AS c
INNER JOIN Order As o
      ON c.id = o.customer_id
WHERE o.order_filled = 1

如何在order_web和订单上使用Union组合这两个更新？

使用Microsoft SQL Server Management Studio

Answer 1

你不需要UINION - 用一对外连接替换内连接应该这样做：

UPDATE c
SET c.order_status = 1
FROM Customer AS c
LEFT OUTER JOIN Order_Web As ow ON c.id = ow.customer_id
LEFT OUTER JOIN Order As o ON c.id = o.customer_id
WHERE ow.order_filled = 1 OR o.order_filled = 1

您还可以使用WHERE EXISTS，如下所示：

UPDATE c
SET c.order_status = 1
FROM Customer AS c
WHERE EXISTS (
    SELECT 1 FROM Order_Web As ow WHERE c.id = ow.customer_id AND ow.order_filled = 1 
) OR EXISTS (
    SELECT 1 FROM Order As o WHERE c.id = o.customer_id AND o.order_filled = 1
)

如果您必须使用UNION，则可以按以下方式执行此操作：

UPDATE c
SET c.order_status = 1
FROM Customer AS c
WHERE c.id in (
        SELECT ow.id FROM Order_Web As ow WHERE ow.order_filled = 1 
    UNION
        SELECT o.id FROM Order As o WHERE o.order_filled = 1
)

或与JOIN相同的人：

UPDATE c
SET c.order_status = 1
FROM Customer AS c
JOIN (
        SELECT ow.id AS id FROM Order_Web As ow WHERE ow.order_filled = 1 
    UNION
        SELECT o.id AS id FROM Order As o WHERE o.order_filled = 1
) AS ids ON ids.id = c.id

Answer 2

UPDATE  c
SET     c.order_status = 1
FROM    (
        SELECT  customer_id
        FROM    order_web
        WHERE   order_filled = 1
        UNION
        SELECT  customer_id
        FROM    order
        WHERE   order_filled = 1
        ) o
JOIN    customer c
ON      c.id = o.customer_id

Answer 3

您可以将联合查询放入子查询中。

update customer
c.order_status = 1
where id in 
(union query goes here)

在SQL中使用Union执行UPDATE

3 个答案: