怎樣查詢數據庫中重復的數據？1、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 peoplewhere peopleId in (select

怎樣查詢數據庫中重復的數據？

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

2、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)

3、查找表中多余的重復記錄（多個字段）

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

SQL數據庫多表連接查詢?yōu)槭裁磾祿貜停?/h2>

1、用select語句，查看兩個表中的數據，確認下來的結果是每個表中都只有兩行數據；

2、嘗試著用最常用的兩表結合查詢方式來看看結果----結果重復出現，并且結果錯誤：select a.pono，a.p_name，a.p_kg as 系統(tǒng)重量，b.p_kg as 實際重量 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 實際重量、 from test1 as a 、full join test2 as b on a.pono = b.sono、and a.p_name = b.p_name。