sql 查出一張表中重復的所有記錄數據

在面試的時候碰到一個問題，就是

寫一張表中有id和name 兩個字段，查詢出name重復的所有數據，現在列下：

select * from xi a where 
(a.username) in  (select username from xi group by username  having count(*) > 1)

• 查詢出所有數據進行分組之后，和重復數據的重復次數的查詢數據，先列下

select  count(username) as '重復次數',username from xi 
group by username  having count(*)>1 order by username desc

查詢及刪除重復記錄的方法大全

• 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)

• 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)

• 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)

• 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)

• 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)