C＃SQL如何选择和处理N条记录，然后对其进行更新？

Question

I retrieve some records by running this query:

SELECT * FROM [MyTable] order by [Date] OFFSET N ROWS FETCH NEXT 500 ROWS ONLY

Where N is a number that starts from 0 and increment by 500. There are multiple instances of this application and each instance gets 500 records.

Now the question is, how do I update the retrieved records? The records don't have primary key. I tried something like this but the syntax isn't right:

UPDATE [MyTable] SET [status] = 1 order by [Date] OFFSET N ROWS FETCH NEXT 500 ROWS

Note: I can't use WHERE status = 0 because I want one instance to only deal with the records it retrieved.

Any idea?

Answer 1

You could try something like this:

UPDATE x
 SET [status] = 1
FROM (
      SELECT * FROM [MyTable] order by [Date] OFFSET N ROWS FETCH NEXT 500 ROWS ONLY
      ) x

Answer 2

UPDATE x
SET x.[status] = 1
OUTPUT deleted.*
FROM
    (
        SELECT * 
        FROM [MyTable] 
        WHERE 
            [status] = 0 
        ORDER BY [Date] 
        OFFSET N ROWS FETCH NEXT 500 ROWS ONLY
    ) x;

Be careful though, your "fetch next" is preventing any rows from being returned if there are not at least 500 to return. Maybe that's what you want.