Question

I have my MAIN table T1 from which I am doing select of many fields:

ID
1000

I have table T2:

ID      SERVICE
1000    IPTV
1000    VOIP

I have table T3:

ID      DEVICE
1000    MODEM
1000    ROUTER
1000    DVC

I want to JOIN T1 with T2 or T3 which can but also and might not have values at all !!!!
When they have values I want to have in SELECT number of records of maximum number of records from T2 or T3. So in this case T3 has 3 records which is maximum and I want 3 records in SELECT. (in case that T2 has 3 records that would be maximum in case that T3 has 2 records)

But in my SELECT statement I am having 5 records which I do not want. What is the correct expression for that? My below query returns 5 records (I want 3)

select t1.id,t2.service,t3.device
from t1
left outer join T2 on t1.id=t2.id
left outer join T3 on t1.id=t3.id

Answer 1

SELECT
    t1.id
  , t2.service
  , t3.device
FROM
        t1
    LEFT JOIN
            ( SELECT
                  ROW_NUMBER() OVER (PARTITION BY id ORDER BY service) AS rn
                , id
                , service
              FROM
                  t2
            ) AS t2
        FULL JOIN 
            ( SELECT
                  ROW_NUMBER() OVER (PARTITION BY id ORDER BY device) AS rn
                , id
                , device
              FROM
                  t3
            ) AS t3
          ON  t3.id = t2.id
          AND t3.rn = t2.rn
      ON COALESCE(t2.id, t3.id) = t1.id ;