Question

I have a table called categories that has 3 columns: id, name, parent_id.

ID         name         group_id
==         ==           ==
1          haim         1
2          gil          2
3          alon         1
4          idan         1
5          shai         3
6          adi          2
7          itay         3
8          aviram       1
9          lioz         3
10         amit         2
11         ben          2
12         eran         1

i need to select 2 rows of each group_id in one query so the result would be:

ID         name         group_id
==         ==           ==
1          haim         1
3          alon         1
2          gil          2
6          adi          2
5          shai         3
7          itay         3

it’s very important that it will also be sorted by group_id.

Thanks!

Answer 1

I took in consideration the first and second ID found in the table per each group_id.

SELECT ID, NAME, GROUP_ID
FROM MYTABLE WHERE ID IN (
    SELECT MIN(ID)
    FROM MYTABLE
    GROUP BY GROUP_ID)

UNION ALL

SELECT ID, NAME, GROUP_ID
FROM MYTABLE WHERE ID IN (
    SELECT MIN(ID)
    FROM MYTABLE
    WHERE ID NOT IN (
      SELECT MIN(ID)
      FROM MYTABLE
      GROUP BY GROUP_ID
      )
    GROUP BY GROUP_ID)
ORDER BY GROUP_ID