1. 查询表中重复数据
   select * from employee where employeeId in (select employeeId from employee group by employeeId having count(employeeId) > 1)

2. 删除表中多余的重复记录，重复记录是根据单个字段（employeeId）来判断，只留有rowid最小的记录
   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)

3. 查找表中多余的重复记录（多个字段）
   select * from employee e
   where (e.employeeId,e.phoneNo) in (select employeeId,phoneNo from employee group by employeeId,phoneNo having count(*) > 1)

4. 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 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)

5. 查找表中多余的重复记录（多个字段），不包含rowid最小的记录
   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.字段1, t.字段2, … , t.字段n) in (select 字段1, 字段2, … , 字段n from table group by 字段1, 字段2, … , 字段n having count(*) > 1)
and rowid not in (select min(rowid) from table group by 字段1, 字段2, … , 字段n having count(*)>1)

此外:

如果只是查询的时候, 不显示重复, 只需select distinct 字段 from table….