怎樣查詢數(shù)據(jù)庫中重復(fù)的數(shù)據(jù)？1、查找表中多余的重復(fù)記錄，重復(fù)記錄是根據(jù)單個(gè)字段（peopleId）來判斷select * from peoplewhere peopleId in (select

怎樣查詢數(shù)據(jù)庫中重復(fù)的數(shù)據(jù)？

1、查找表中多余的重復(fù)記錄，重復(fù)記錄是根據(jù)單個(gè)字段（peopleId）來判斷

select * from peoplewhere peopleId in (select peopleId from people group by peopleId having count (peopleId) > 1)

2、刪除表中多余的重復(fù)記錄，重復(fù)記錄是根據(jù)單個(gè)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(fù)記錄（多個(gè)字段）

select * from vitae awhere (a.peopleId，a.seq) in (select peopleId，seq from vitae group by peopleId，seq having

SQL數(shù)據(jù)庫多表連接查詢?yōu)槭裁磾?shù)據(jù)會重復(fù)？

1、用select語句，查看兩個(gè)表中的數(shù)據(jù)，確認(rèn)下來的結(jié)果是每個(gè)表中都只有兩行數(shù)據(jù)；

2、嘗試著用最常用的兩表結(jié)合查詢方式來看看結(jié)果----結(jié)果重復(fù)出現(xiàn)，并且結(jié)果錯(cuò)誤：select a.pono，a.p_name，a.p_kg as 系統(tǒng)重量，b.p_kg as 實(shí)際重量 from test1 a，test2 b where a.pono=b.sono；

3、執(zhí)行完整代碼，可以得出結(jié)果，select isnull(a.pono，b.sono) as pono，isnull(a.p_name，b.p_name) as p_name， a.p_kg as 系統(tǒng)重量、 b.p_kg as 實(shí)際重量、 from test1 as a 、full join test2 as b on a.pono = b.sono、and a.p_name = b.p_name。