基于SQL Server中另一列值的条件返回更新的列值

你可以使用 in 操作员:

SELECT DATEADD(MM, 1, valid_till) 
FROM   referrals
WHERE  referrer_id IN (SELECT   referrer_id
                       FROM     referrals
                       GROUP BY referrer_id
                       HAVING   COUNT(*) > 2)

或者,如果您真的需要更新表,而不仅仅是查询添加的月份,您可以在 update 声明:

UPDATE referrals 
SET    valid_till = DATEADD(MM, 1, valid_till) 
WHERE  referrer_id IN (SELECT   referrer_id
                       FROM     referrals
                       GROUP BY referrer_id
                       HAVING   COUNT(*) > 2)

join . 但是,我不确定表之间匹配的确切条件是什么:

select DATEADD(month, 1, valid_till)
from Referrals r join
     (select [referrer_id(same as profile id)], count([referrer_id(same as profile id)]) 
      from referrals
      group by [referrer_id(same as profile id)]
      having count([referrer_id(same as profile id)]) > 2
     ) rr
     on rr.ref_id = [referrer_id(same as profile id)];