Oracle 删除重复数据的几种方法

去重第一种：distinctcreate table tmp_t3 as select distinct * from t3;drop table t3;alter table tmp_t2 rename to t3;– 第二种，用rowiddelete from t2    where rowid <>( select min(rowid)                     from t2 b                     where b.c1 = t2.c1                       and b.c2 = t2.c2 ) —第三种， 用rowid + group by 的方法delete from T2    where rowid not in (select min(rowid)    from t2 group by c1,c2 ); delete from t2 where not exists (select 1 from (select min(rowid) rid from t2 group by c1,c2) b where b.rid=t2.rowid) —第四种， 用分析函数delete from t2 where rowid in (select b.rd from (select rowid rd,row_number() over(partition by c1,c2 order by c1) rn from t2) b where b.rn > 1);