查詢表中重複資料 
select * from employee where employeeId in (select employeeId from employee group by employeeId having count(employeeId) > 1)

刪除表中多餘的重複記錄，重複記錄是根據單個欄位（employeeId）來判斷，只留有rowid最小的記錄 
delete from employee where employeeId in (select employeeId from employee group by employeeId having count(employeeId) > 1) 
and rowid not in (select min(rowid) from employee group by employeeId having count(employeeId )>1)

查詢表中多餘的重複記錄（多個欄位） 
select * from employee e 
where (e.employeeId,e.phoneNo) in (select employeeId,phoneNo from employee group by employeeId,phoneNo having count(*) > 1)

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 employee e 
where (e.employeeId, e.phoneNo) in (select employeeId, phoneNo from employee group by employeeId,phoneNo having count(*) > 1) 
and rowid not in (select min(rowid) from employee group by employeeId,phoneNo having count(*)>1)

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 employee e 
where (e.employeeId,e.phoneNo) in (select employeeId, phoneNo from employee group by employeeId,phoneNo having count(*) > 1) 
and rowid not in (select min(rowid) from employee group by employeeId,phoneNo having count(*)>1)

通用:

delete from table t 
where (t.欄位1, t.欄位2, … , t.欄位n) in (select 欄位1, 欄位2, … , 欄位n from table group by 欄位1, 欄位2, … , 欄位n having count(*) > 1)
and rowid not in (select min(rowid) from table group by 欄位1, 欄位2, … , 欄位n having count(*)>1)

此外:

如果只是查詢的時候, 不顯示重複, 只需select distinct 欄位 from table….
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作者：關耳木 
來源：CSDN 
原文：https://blog.csdn.net/germoo/article/details/79960480 
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