SQL重復記錄查詢
1、查找表中多余的重復記錄，重復記錄是根據單個字段（peopleId）來判斷
| select * from people where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1) |
例二：
| select * from testtable where numeber in (select number from people group by number having count(number) > 1 ) |
可以查出testtable表中number相同的記錄
2、刪除表中多余的重復記錄，重復記錄是根據單個字段（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) |
3、查找表中多余的重復記錄（多個字段）
| select * from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1) |
4、刪除表中多余的重復記錄（多個字段），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、查找表中多余的重復記錄（多個字段），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表中存在一個字段“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”值存在重復的項；
| 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 |
(三)
方法一
| declare @max integer,@id integer declare cur_rows cursor local for select 主字段,count(*) from 表名 group by 主字段 having count(*) >； 1 open cur_rows fetch cur_rows into @id,@max while @@fetch_status=0 begin select @max = @max -1 set rowcount @max delete from 表名 where 主字段 = @id fetch cur_rows into @id,@max end close cur_rows set rowcount 0 |
方法二
有兩個意義上的重復記錄，一是完全重復的記錄，也即所有字段均重復的記錄，二是部分關鍵字段重復的記錄，比如Name字段重復，而其他字段不一定重復或都重復可以忽略。
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