1、查詢表中重復數據（單字段）
Select * From 表 Where 字段1 In (Select 字段1 From 表 Group By 字段1 Having Count(字段1) > 1)
2、刪除表中多余的重復記錄，只留有rowid最小的記錄（單字段）
Delete From 表
Where 字段1 In (Select 字段1 From 表 Group By 字段1 Having Count(字段1) > 1) And
Rowid Not In (Select Min(Rowid) From 表 Group By 字段1 Having Count(字段1) > 1)
3、查找表中多余的重復記錄（多個字段）
Select * From 表 a Where (a.字段1, a.字段2) In (Select 字段1, 字段2 From 表 Group By 字段1, 字段2 Having Count(*) > 1)
4、刪除表中多余的重復記錄，只留有rowid最小的記錄（多個字段）
Delete From 表 a
Where (a.字段1, a.字段2) In (Select 字段1, 字段2 From 表 Group By 字段1, 字段2 Having Count(*) > 1) And
Rowid Not In (Select Min(Rowid) From 表 Group By 字段1, 字段2 Having Count(*) > 1)
5.刪除多於的重復記錄（單個字段，多個字段）
delete from table where id not in ( select min(id) from table group by name)
或者
delete from table where id not in ( select min(id) from table group by 字段1，字段2)
6.刪除多余的重復記錄（單個字段，多個字段）
delete from table where id in ( select max(id) from table group by name 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 表 a
Where (a.字段1, a.字段2) In (Select 字段1, 字段2 From 表 Group By 字段1, 字段2 Having Count(*) > 1) And
Rowid Not In (Select Min(Rowid) From 表 Group By 字段1, 字段2 Having Count(*) > 1)
查單個字段的重復次數
Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1
