sql 2005刪除重複記錄 保留其中一條

有個friend表，字段有id，userid，friendid，status，id只是用來標識的，userid和friendid是varchar類型的，status是int類型的
示例如下：
id       userid         friendid       status
1        TERRY       123               1
2        TERRY        123               1
3        DIMA            SKY              0
4        DIMA             SKY             0

怎樣可以變成
id       userid         friendid       status
1        TERRY       123               1
3        DIMA            SKY              0

 

delete from friend where id in (select id from
(select id,userid, row_number() over(partition by userid order by id) as rn from friend )  as a where rn > 1)