sql - 删除SQL循环

Question

我只想为每个 clientid 保留 1000 个条目。下面的代码执行了我想要的操作，但不循环遍历 clientid，而是保留任何客户端的总数 1000。

有没有办法在sql中做到这一点？有人告诉我我需要一个光标，但我希望不需要。

DECLARE @ids TABLE ( id int )
DECLARE @clients TABLE ( clientid varchar(20) )

INSERT INTO @clients (clientid)
SELECT select distinct clientid FROM tRealtyTrac 

INSERT INTO @ids (id)
SELECT top 1000 id FROM tRealtyTrac WHERE clientid in (select clientid from @clients)

DELETE trealtytrac WHERE id NOT IN (select id from @ids)

Answer 1

这是 SQL Server 2005 或更高版本吗？像这样的东西怎么样？

INSERT INTO @ids (id)
SELECT id FROM (
    SELECT id, RANK() OVER (PARTITION BY clientid ORDER BY id) AS Rank FROM tRealtyTrac
) t
WHERE t.Rank <= 1000