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查出重复记录
SQL》 select rowid，bm，mc from a where a.rowid！=（select max（rowid） from a b where a.bm=b.bm and a.mc=b.mc）;
ROWID BM MC
------------------ ---- --------------------
000000D5.0000.0002 1111 1111
000000D5.0001.0002 1112 1111
000000D5.0002.0002 1113 1111
000000D5.0003.0002 1114 1111
删除重复记录
SQL》 delete from a a where a.rowid！=（select max（rowid） from a b where a.bm=b.bm and a.mc=b.mc）;
删除4个记录。
SQL》 select rowid，bm，mc from a;
ROWID BM MC
------------------ ---- --------------------
000000D5.0004.0002 1111 1111
000000D5.0005.0002 1112 1111
000000D5.0006.0002 1113 1111
000000D5.0007.0002 1114 1111
根据单个属性字段判断重复性：
select * from tableName
where columnName in (select columnName from tableName
group by columnName having count(columnName) > 1);
根据多个属性字段判断重复性:
select * from tableName a
where (a.columnName1, a.columnName2) in (select columnName1, columnName2
from tableName group by columnName1, columnName2 having count(*) > 1);
所有属性完全相同的情况：
select distinct * from td_tyorg;
删除某个字段相同记录(只留下rowid最小的记录，其中rowid为oracle系统自建的字段)：
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);
删除表中多余的重复记录（多个字段），只留有rowid最小的记录:
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);
如果该表需要删除重复的记录（重复记录保留1条），可以按以下方法删除
select distinct *
into #Tmp
from tableName drop table tableName
select * into tableName from #Tmp drop table #Tmp
找出在表product中字段product_id和saler_id中重复的记录？
即product_id saler_id
-----------------------------
22 aa
22 aa
33 aa
44 aa
55 bb
55 bb
66 bb
77 bb
如何查出product_id重复的记录！
select product_id from product
group by product_id,saler_id having count(*)>1
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