Question

我在MS SQL 2008中使用sql compact database（sdf）。在'Job'表中，每个id都有多个作业。有一个系统定期将工作添加到表中。

我想通过'datecompleted'保留每个id订单的10条最新记录并删除其余记录

我如何构建我的查询？使用#temp表和游标

失败

Answer 1

~~如下所示：~~

~~DELETE FROM Job WHERE NOT id IN ( SELECT TOP 10 id FROM Job ORDER BY datecompleted)~~

~~这假设您使用的是3.5，因为嵌套的SELECT仅适用于此版本或更高版本。~~

我没有正确地阅读这个问题。我怀疑CTE的更多内容将使用类似的逻辑来解决问题。您希望构建一个标识要保留的记录的查询作为起点。

Using CTE on SQL Server Compact 3.5

Answer 2

嗯它快到了圣诞节，所以这是我给你的礼物，一个示例脚本，展示了我相信你正在努力实现的目标。不，我没有一头白色蓬松的胡须; - ）

CREATE TABLE TestJobSetTable
(
    ID INT IDENTITY(1,1) not null PRIMARY KEY,
    JobID INT not null,
    DateCompleted DATETIME not null
);

--Create some test data
DECLARE @iX INT;
SET @iX = 0
WHILE(@iX < 15)
BEGIN
    INSERT INTO TestJobSetTable(JobID,DateCompleted) VALUES(1,getDate())
    INSERT INTO TestJobSetTable(JobID,DateCompleted) VALUES(34,getDate())
    SET @iX = @iX + 1;
        WAITFOR DELAY '00:00:0:01'
END
--Create some more test data, for when there may be job groups with less than 10 records.
SET @iX = 0
WHILE(@iX < 6)
BEGIN
    INSERT INTO TestJobSetTable(JobID,DateCompleted) VALUES(23,getDate())
    SET @iX = @iX + 1;
        WAITFOR DELAY '00:00:0:01'
END

--Review the data set
SELECT * FROM TestJobSetTable;


--Apply the deletion to the remainder of the data set.
WITH TenMostRecentCompletedJobs AS
(

    SELECT ID, JobID, DateCompleted
    FROM TestJobSetTable A
    WHERE ID in
    (   
        SELECT TOP 10 ID 
        FROM TestJobSetTable
        WHERE JobID = A.JobID
        ORDER BY DateCompleted DESC
    )
)
--SELECT * FROM TenMostRecentCompletedJobs ORDER BY JobID,DateCompleted desc;
DELETE FROM TestJobSetTable 
WHERE ID NOT IN(SELECT ID FROM TenMostRecentCompletedJobs)

--Now only data of interest remains
SELECT * FROM TestJobSetTable

DROP TABLE TestJobSetTable;

删除旧记录并保留10个最新的sql compact

2 个答案: