根据第一列的重复值匹配第二列的重复值

Question

我有table这样的

CREATE TABLE table1 (
  `ID` VARCHAR(100),
  `Val` VARCHAR(100),
  `Val2` VARCHAR(100)
);

INSERT INTO table1
  (`ID`, `Val`, `Val2`)
VALUES
  ('1','4788','90'),
  ('2','4788','90'),
  ('10','4788','10'),
  ('20','111','10'),
  ('30','111','10'),
  ('57','89','89111'),
  ('59','89','89111'),
  ('60','89','10'),
  ('2','900','7000'),
  ('4','900','7001');

对于这个 table 我有两个条件，即：

Val 列必须是重复值 AND，
Val2 列必须重复

所以我的目标是 return 如果两个条件都满足的数据。如果列 val 有重复值并且列 val2 有重复值并且每列在他自己的行上。

我的查询是这样的

select t1.* from table1 t1
where exists (select 1 from table1 where id <> t1.id and val = t1.val)
and exists (
  select 1 from table1 
  where val = t1.val and val2 in (select val2 from table1 group by val2 having count(*) > 1)
)

结果是这样的

ID  Val Val2
1   4788    90
2   4788    90
10  4788    10
20  111 10
30  111 10
57  89  89111
59  89  89111
60  89  10

如您所见，列彼此不匹配

我希望结果数据是这样的

ID  Val Val2
1   4788    90
2   4788    90
20  111 10
30  111 10
57  89  89111
59  89  89111

这是我的 fiddle

Answer 1

您可以起诉 group by 并要求检查重复项

    select  val, val2 
    from  table1 

    group by val, val2 
    having count(*) > 1

然后

select t1.* 
from table1 t1
inner join (
    select  val, val2 
    from  table1 

    group by val, val2 
    having count(*) > 1  
) t on t.val =t1.val and t.val2 = t1.val2

Answer 2

您需要 having 和 join。这是 demo.

select 
   t.* 
from table1 t
join (
    select  
       val, val2 
    from table1 
    group by 
       val, val2 
    having count(*) > 1  
) t1 
on t.val = t1.val 
and t.val2 = t1.val2

输出：

| ID  | Val  | Val2  |
| --- | ---- | ----- |
| 1   | 4788 | 90    |
| 2   | 4788 | 90    |
| 20  | 111  | 10    |
| 30  | 111  | 10    |
| 57  | 89   | 89111 |
| 59  | 89   | 89111 |

Answer 3

您 exists 的方向是正确的。你只是把逻辑复杂化了：

select t1.*
from table1 t1
where exists (select 1
              from table1 tt1
              where tt1.id <> t1.id and
                    tt1.val = t1.val and
                    tt1.val2 = t1.val2
             ) ;

您想要两个值的副本在同一行。因此，这是一个 exists 子句。

Here 是一个 db<>fiddle.

根据第一列的重复值匹配第二列的重复值

Match duplicate value from the second column based on duplicate value from first colum

mysql

sql

group-by

having

mysql-5.7