SQL查询时去除重复值

erina.pan

方法1：  delete from test  where id not in (select max(id) from test with(nolock) group by bookname,nuthor having count(id) > 0)

方法2：WITH myd AS
(
    SELECT ROW_NUMBER()
    OVER(PARTITION BY bookname,nuthor ORDER BY ID )
    AS NUM,* FROM test
)
DELETE FROM myd
WHERE NUM != 1