如何获得具有两个对应列的记录，这些列在 SQL 中是多个？

Question

For example, I have two tables:

ID | Name
------------
1  | test 1 
2  | test 2 

ID2| ID | Age
--------------
1  | 1  | 18
2  | 1  | 18
3  | 1  | 19
4  | 2  | 18
5  | 2  | 19

I want to have all records that have columns which are multiple in name with age but I don't know how to do that.

I want an output like this:

Name     | Age
--------------------
test 1   | 18
test 1   | 18

Can anyone help me?

Answer 1

Try following query:

Select t1.*, t2.* 
from table1 t1
join table2 t2
on  t1.id = t2.id
join (select id, age
      from table2
      group by id, age
      having count(*) > 1
     ) t3
on t1.id = t2.id and t2.id = t3.id and t2.age = t3.age

Answer 2

Use exists :

select t.*
from t
where exists (select 1
              from t t2
              where t2.name = t.name and t2.age = t.age and
                    t2.id <> t.id
             );

With an index on (name, age, id) , this should be the fastest approach.

Answer 3

You can also use an IN on tupples.

And a GROUP BY can be combined with a HAVING to only get those that have duplicate (name, age).

SELECT t1.Name, t2.Age
FROM YourTable2 t2
LEFT JOIN YourTable1 t1 ON t1.ID = t2.ID
WHERE (t2.ID, t2.Age) IN (
      SELECT ID, Age
      FROM YourTable2
      GROUP BY ID, Age
      HAVING COUNT(*) > 1
  );