查詢刪除表中重複記錄

最高效刪除重複記錄的方法，使用為例rowid

DELETE FROM EMP E WHERE E.ROWID > (SELECT MIN(X.ROWID) FROM EMP X WHERE X.EMP_NO = E.EMP_NO);

        1、查詢表中多餘的重複記錄，重複記錄是根據單個欄位（peopleId）來判斷
　　select * from people
　　where peopleId in (select   peopleId from   people group by   peopleId having count(peopleId) > 1)
　　2、刪除表中多餘的重複記錄，重複記錄是根據單個欄位（peopleId）來判斷，只留有 rowid最小的記錄
　　delete from people
　　where peopleId in (select   peopleId from people group by   peopleId   having count(peopleId) > 1)
　　and rowid not in (select min(rowid) from   people group by peopleId having count(peopleId )>1)
　　注:rowid為oracle自帶不用該.....
　　3、查詢表中多餘的重複記錄（多個欄位）
　　select * from vitae a
　　where (a.peopleId,a.seq) in   (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
　　4、刪除表中多餘的重複記錄（多個欄位），只留有rowid最小的記錄
　　delete from vitae a
　　where (a.peopleId,a.seq) in   (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
　　and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)
　　5、查詢表中多餘的重複記錄（多個欄位），不包含rowid最小的記錄
　　select * from vitae a
　　where (a.peopleId,a.seq) in   (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
　　and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)
　　(二)
　　比方說
　　在A表中存在一個欄位“name”，
　　而且不同記錄之間的“name”值有可能會相同，
　　現在就是需要查詢出在該表中的各記錄之間，“name”值存在重複的項；
　　Select Name,Count(*) From A Group By Name Having Count(*) > 1
　　如果還查性別也相同大則如下:
　　Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1