sql表分割数据查重
2022-07-22阅读(905)
问:SQL查询语句,怎样查询重复数据
- 答:1、第一步,打开数据库,并创建一个包含重复数据的新用户表,见下图,转到下面的步骤。
2、第二步,执行完上面的操作之后,输入如下红框中的SQL语句,然后单击运行按钮,以查看数据库中用户表中的重复数据,见下图,转到下面的步骤。
3、第三步,执行完上面的操作之后,查找出了具有重复名称的数据,见下图,转到下面的步骤。
4、第四步,执行完上面的操作之后,可以使用如下语句来去除重复数据,见下图,转到下面的步骤。
5、第五步,执行完上面的操作之后,最终删除了同一类中的重复数据,见下图。这样,就解决了这个问题了。
- 答:selectid,name,memo
fromA
whereidin(selectidfromAgroupbyidhavingcount(1)>=2)
1查询 abcd相同的记录:
select * from F where a=b and b=c and c=d
2查询有重复数据的记录
select * from F group by a,b,c,d having count(*)>1
3取出数据过滤到重复的数据
select distinct a,b,c,d from f - 答:我们假如在goods表中id是唯一的,其中name可能会相同,现在要查出name存在重复的所有条目,sql可以这样写,可能理解不同,仅供参考
select id,name from goods WHERE name in ( SELECT name FROM goods GROUP BY name HAVING COUNT(name) > 1) - 答:select id,count(1) as num from table where num>1 group by id
- 答:select count(*),id from 表名 group by id having count(*)>1
- 答:select id, name, memo
from A
where id in (select id from A group by id having count(1) >= 2) - 答:是要把重复的ID查出来嘛?
select id
from A
group by id
Having count(id)>1 - 答:select id,count(1) 重复次数 from A group by id having count(1)>1;
查询出来的结果都是id重复的,重复次数 中的数值就是重复了多少次。 - 答:select id,count(*) from A group by A.id havinig count(*)>1;
- 答:select id, name, memo from A where id in (select id from A group by id having count(1) >= 2)
- 答:查询重复数据,方法如下:
select * from [表A] where id in (select id from [表A] group by id having count(id) >1 )
问:sql 表中怎么根据多个字段查询重复数据,
- 答:查重复的数据
select a,b,c,d,e,f
from a
group by a,b,c,d,e,f
having count(*)>1
正解~!~
在oracle 中剔重查数据sql
select a, b, c, d, e, f from (select a, b, c, d, e, f, row_number() over(partition by a,b,c,d,e,f order by rowid) rn
from a) t where rn = 1; - 答:select max(a),max(b)等字段 from A
group by a,b,c,d
max 是聚合函数··
如果值是数字 建议换个聚合函数就行·· - 答:select a,b,c,d,e,f
from a
group by a,b,c,d,e,f
having count(*)>1
正解~!~ - 答:使用 degree字段分组查询,再 top 3
select top 3 degree,count(degree) as 人数
from student
group by degree
order by degree - 答:select a,b,c,d,e,f
from a
group by a,b,c,d,e,f
having count(*)>1
问:两个表SQL查重
- 答:select a.A ,a.b,a.c,b.a as 'd',b.b as 'e',b.c as 'f'
from 表1 a,表二 b - 答:select a.A ,a.b,a.c,b.a as 'D',b.b as 'E',b.c as 'F'
from 表1 a
outer join 表二 b
on a.A=b.A and a.B=b.B and a.C=b.C
问:sql 从关系表中取出的数据是重复的,如何去除重复的数据
- 答:用distinct或者group by可以剃重
- 答:如果是两个表比较常用的方法是:in和exists语句
exists语句:
delete from a where exists (select * from b where a.bm=b.bm and a.mc=b.mc);
in语句:
delete from a where (bm,mc) in (select bm,mc from b);
如果是单表,就一条命令:
select distinct 字段名1,字段名2 from 表格 order by 字段名1
distinct 字段名1,意思是只显示一次字段名1,显示的是第一次出现的 - 答:select distinct * from yourtablename
问:SQL查重语句
- 答:按手机号码分组查询。count(*)大于1的就是有重复的手机号码。
- 答:可以看看数据库嵌套查询之类;
select * from B where phonenumber in(select phonenumber from A);
其中的* 可以改成你要的名字,住址之类;
A,B代表两个表;
phonenumber代表两表中存电话号码的列名;
试一下。 - 答:select b.姓名,b.地址,b.手机号 from a,b where a.手机号=b.手机号