delete old records and keep 10 latest in sql compact - sql

Question

i'm using a sql compact database(sdf) in MS SQL 2008.
in the table 'Job', each id has multiple jobs.
there is a system regularly add jobs into the table.
I would like to keep the 10 latest records for each id order by their 'datecompleted'
and delete the rest of the records
how can i construct my query? failed in using #temp table and cursor

Answer 1

Well it is fast approaching Christmas, so here is my gift to you, an example script that demonstrates what I believe it is that you are trying to achieve. No I don't have a big white fluffy beard ;-)
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;

Answer 2

How about something like:
DELETE FROM
Job
WHERE NOT
id IN (
SELECT TOP 10 id
FROM Job
ORDER BY datecompleted)
This is assuming you're using 3.5 because nested SELECT is only available in this version or higher.
I did not read the question correctly. I suspect something more along the lines of a CTE will solve the problem, using similar logic. You want to build a query that identifies the records you want to keep, as your starting point.
Using CTE on SQL Server Compact 3.5