Question

我想过滤SQL中的数据，以便我只有IsReady字段为真的每个厚度的最新行。

编辑：我正在为所有需要知道的人使用MSSQL 2008服务器

我的数据是这样的：

+--+----------+-----------+----------+-------+
|ID|SupplierID|ThicknessID|DateTime  |IsReady|
+--+----------+-----------+----------+-------+
|01|1         |1          |01/01/1990|1      |
|02|1         |1          |01/01/2012|0      |
|03|1         |2          |01/01/1990|1      |
|04|1         |2          |01/01/2012|1      |

根据提供的数据，SQL代码应返回以下内容：

+--+----------+-----------+----------+-------+
|ID|SupplierID|ThicknessID|DateTime  |IsReady|
+--+----------+-----------+----------+-------+
|01|1         |1          |01/01/1990|1      |
|04|1         |2          |01/01/2012|1      |

希望这是足够的信息让你理解，如果不是只是评论

Answer 1

SELECT A.* FROM TABLE A,
              (SELECT ThicknessID,MAX(DateTime) AS MaxDateTime
               FROM TABLE 
               WHERE IsReady=1
               GROUP BY ThicknessID    
              ) B      
WHERE A.ThicknessID=B.ThicknessID AND
      A.MaxDateTime = B.DateTime;

Answer 2

SELECT t.*
FROM Table t
WHERE IsReady=1
AND t.ID=(SELECT TOP 1 t2.ID
          FROM Table t2
          WHERE t2.IsReady=1
          AND t.ThicknessID=t2.ThicknessID
          ORDER BY DateTime DESC)

Answer 3

假设您希望每个SupplierID分别包含行：

select t.ID,
    t.SupplierID,
    t.ThicknessID,
    t.[DateTime],
    t.IsReady
from MyTable t
inner join (
    select SupplierID,
        ThicknessID,
        max([DateTime]) as MaxDateTime
    from MyTable
    where IsReady = 1
    group by SupplierID,
        ThicknessID
    ) a on t.ThicknessID = a.ThicknessID
    and t.SupplierID = a.SupplierID
    and t.MaxDateTime = a.[DateTime]

Answer 4

所选查询将正常工作。但是这个查询将更快地运行并且将使用更少的资源

select distinct (SupplierID, ThicknessID) * from
(
    select * from Table1 where IsReady = 1
    order by [DateTime] desc
)

我试过这个并且性能更高

使用MSSQL过滤SQL数据以获取每个备用ID的最新信息

4 个答案: