查询表中相同数据的sql语句

今天药忘吃喽~ 2022-09-18 12:54 314阅读 0赞
  1. --1、查找表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断
  2. select * from people
  3. where peopleId in (select peopleId from people group by peopleId having count (peopleId) > 1)
  4. --2、删除表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断,只留有rowid最小的记录
  5. delete from people
  6. where peopleId in (select peopleId from people group by peopleId having count (peopleId) > 1)
  7. and rowid not in (select min(rowid) from people group by peopleId having count(peopleId )>1)
  8. --3、查找表中多余的重复记录(多个字段)
  9. select * from vitae a
  10. where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having
  11. count(*) > 1)
  12. --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
  13. delete from vitae a
  14. where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
  15. and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)
  16. --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
  17. select * from vitae a
  18. where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having
  19. count(*) > 1)
  20. and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)
  21. /**(二)
  22. 比方说
  23. 在A表中存在一个字段“name”,
  24. 而且不同记录之间的“name”值有可能会相同,
  25. 现在就是需要查询出在该表中的各记录之间,“name”值存在重复的项;**/
  26. Select Name,Count(*) From A Group By Name Having Count(*) > 1
  27. --如果还查性别也相同大则如下:
  28. Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1
  29. --(三)
  30. --方法一
  31. declare @max integer,@id integer
  32. declare cur_rows cursor local for select 主字段,count(*) from 表名 group by 主字段 having
  33. count(*) > 1
  34. open cur_rows
  35. fetch cur_rows into @id,@max
  36. while @@fetch_status=0
  37. begin
  38. select @max = @max -1
  39. set rowcount @max
  40. delete from 表名 where 主字段 = @id
  41. fetch cur_rows into @id,@max
  42. end
  43. close cur_rows
  44. set rowcount 0
  45. /**方法二
  46. 有两个意义上的重复记录,一是完全重复的记录,也即所有字段均重复的记录,
  47. 二是部分关键字段重复的记录,比如Name字段重复,而其他字段不一定重复或都重复可以忽略。**/
  48.   --1、对于第一种重复,比较容易解决,使用
  49. select distinct * from tableName
  50.   --就可以得到无重复记录的结果集。
  51.   --如果该表需要删除重复的记录(重复记录保留1条),可以按以下方法删除
  52. select distinct * into #Tmp from tableName
  53. drop table tableName
  54. select * into tableName from #Tmp
  55. drop table #Tmp
  56.   --发生这种重复的原因是表设计不周产生的,增加唯一索引列即可解决。
  57.   --2、这类重复问题通常要求保留重复记录中的第一条记录,操作方法如下
  58.   --假设有重复的字段为Name,Address,要求得到这两个字段唯一的结果集
  59. select identity(int,1,1) as autoID, * into #Tmp from tableName
  60. select min(autoID) as autoID into #Tmp2 from #Tmp group by Name,autoID
  61. select * from #Tmp where autoID in(select autoID from #tmp2)
  62.   --最后一个select即得到了NameAddress不重复的结果集(但多了一个autoID字段,实际写时可以写
  63. --在select子句中省去此列)
  64. --(四)查询重复
  65. select * from tablename
  66. where id in (select id from tablename group by id having count(id) > 1)

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