MySQL查詢表內重復記錄 (一)
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 people where 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,只留有一個記錄 delete from people where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1) and min(id) not in (select id 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 a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1) 4、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) 5、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)
(二) 比方說 在A表中存在一個字段“name”, 而且不同記錄之間的“name”值有可能會相同, 現在就是需要查詢出在該表中的各記錄之間,“name”值存在重復的項;
Select Name,Count(*) From A Group By Name Having Count(*) > 1
如果還查性別也相同大則如下:
Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1
(三) 方法一
declare @max integer,@id integer declare cur_rows cursor local for select 主字段,count(*) from 表名 group by 主字段 having count(*) >; 1 open cur_rows fetch cur_rows into @id,@max while @@fetch_status=0 begin select @max = @max -1 set rowcount @max delete from 表名 where 主字段 = @id fetch cur_rows into @id,@max end close cur_rows set rowcount 0