oracle_SQL 实验查询及删除重复记录 依据条件 (row)

时间:2021-01-28 14:41:27

除数据库表中的重复记录 根据条件

① 创建表准备数据

创建表 tab_test

-- Create table
create table TAB_TEST
(
ID NUMBER,
NAME NVARCHAR2(10),
VALUE NVARCHAR2(10),
TIME DATE default sysdate not null
)

插入模拟数据

insert into tab_test (ID, NAME, VALUE)values (1, 'aa ', 'vv');
insert into tab_test (ID, NAME, VALUE)values (1, 'aa ', 'vv');
insert into tab_test (ID, NAME, VALUE)values (2, 'bb ', 'vv');
insert into tab_test (ID, NAME, VALUE)values (2, 'bb ', 'vv');
insert into tab_test (ID, NAME, VALUE)values (3, 'cc ', 'vv');
insert into tab_test (ID, NAME, VALUE)values (3, 'cc ', 'vv');
insert into tab_test (ID, NAME, VALUE)values (4, 'dd ', 'vv');
insert into tab_test (ID, NAME, VALUE)values (4, 'dd ', 'vv');

查询数据

oracle_SQL 实验查询及删除重复记录 依据条件 (row)

查询及删除重复记录的SQL语句
查询及删除重复记录的SQL语句
1、查找表中多余的重复记录,重复记录是根据单个字段(id)来判断
select * from tab_test
where id in (select   id from   tab_test group by   id having count(id) > 1)
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

delete from tab_test
where id in (select id from tab_test group by id having count(id) > 1)
and rowid not in (select min(rowid) from tab_test group by id having count(id )>1)

---重新插入数据 
oracle_SQL 实验查询及删除重复记录 依据条件 (row)
====一下sql 对应修改即可
3、查找表中多余的重复记录(多个字段)
select * from vitae a
where (a.peopleId,a.seq) in   (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
4、删除表中多余的重复记录(多个字段),只留有rowid最小的记录
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、查找表中多余的重复记录(多个字段),不包含rowid最小的记录
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)
比方说
在A表中存在一个字段“name”,
而且不同记录之间的“name”值有可能会相同,
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;
Select Name,Count(*) From A Group By Name Having Count(*) > 1
如果还查性别也相同大则如下:
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
方法二
"重复记录"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,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。
  1、对于第一种重复,比较容易解决,使用
select distinct * from tableName
  就可以得到无重复记录的结果集。
  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
select distinct * into #Tmp from tableName
drop table tableName
select * into tableName from #Tmp
drop table #Tmp
  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。
  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
  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
select identity(int,1,1) as autoID, * into #Tmp from tableName
select min(autoID) as autoID into #Tmp2 from #Tmp group by Name,autoID
select * from #Tmp where autoID in(select autoID from #tmp2)
  最后一个select即得到了Name,Address不重复的结果集(但多了一个autoID字段,实际写时可以写在select子句中省去此列)
(四)
查询重复
select * from tablename where id in (
select id from tablename
group by id
having count(id) > 1
)