求解 怎么更新表 设置相同的PersonId ，TestDate字段时间最大的Valid为1 其他的都为0
------解决方案--------------------
UPDATE tablename SET valid = 1 FROM
(SELECT personid , MAX(createdate) AS createdate FROM tablename GROUP BY personid) AS t1
WHERE tablename.personid = t1.personid AND tablename.createdate = t1.createdate
既然版主不方便，我就来码几句