SQL如何使用where条件更新最后一行

问题描述

Update table1 set status='open' where user='test' order by id DESC

我想用 where 条件更新最后一行

解决方法

您可以使用窗口函数row_number()获取id降序的第一行。

with cte as 
(
    select *,row_number()over(order by id desc)rn from table1 
)
Update cte set status='open' where user='test' and rn=1

或者您可以使用子查询来实现相同的结果：

UPDATE table1 SET status='open'
WHERE ID=(SELECT MAX(ID)FROM table1 where user='test') and user='test'

,

为了找到您想要的记录，您必须首先找到您想要的记录，然后在表中更改该记录。为此，您需要创建一个临时表并将所需的记录放入其中，然后使用获得的信息更新该表。

--Container to Insert Id which are to be iterated
Declare @temp1 Table
(
  ID int
)
--Container to Insert records in the inner select for final output

Insert into @temp1 

SELECT top 1 t.id FROM table1 t
WHERE t.user = 'test'
order by t.id desc

-- Keep track of @temp1 record processing
Declare @columnID int
Declare @columnValue varchar(100)

Begin

Set @columnID=(Select Top 1 id From @temp1)
Set @columnValue = 'open'
UPDATE table1 SET status = @columnValue WHERE id = @columnID


Delete @temp1 Where ID=@columnID
End

,

这应该可行，假设 DBMS 是 MySQL

UPDATE table1
SET status = "open"
WHERE id in
    (SELECT *
     FROM
       (SELECT id
        FROM table1
        WHERE USER = "test"
        ORDER BY id DESC
        LIMIT 1) tmp_tbl);