Question

Can we use Order By clause when we are using Select Query in Select List ?

I want to write query like this :-

select col1
     , col2
     , (select colX from table2 where table2.col1=table1.col1 and rownum<2 order by colY desc) 
     , (select colXX from table3 where table3.col1=table1.col1 and rownum<2 order by colYY desc)
from table1;

I can’t join the table. Its just example of what I want.

OK. Here is the thing.
I have following code written in SQL Server . I want to convert it into Oracle.

SELECT
BANK_ADDRESS1= (SELECT top 1 OWNER_ADDRESS1 
            FROM OWNER_ADDRESS OA, BANK_ACCOUNT
            WHERE PAYMENT.BANK_ACCOUNT_ID = BANK_ACCOUNT.BANK_ACCOUNT_ID
                    and BANK_ACCOUNT.BANK_ID = OA.OWNER_ID
                    order by Isnull (OA.primary_addr , 'N') desc),
PAYEE_ADD1 = (  SELECT top 1 OWNER_ADDRESS1 
                FROM OWNER_ADDRESS OA 
                WHERE OA.OWNER_ID = PAYEE_OWNER.OWNER_ID 
                order by Isnull (OA.primary_addr , 'N') desc ),
FROM    PAYMENT 
            inner JOIN PAYEE ON PAYMENT.PAYMENT_ID = PAYEE.PAYMENT_ID
            inner join OWNER PAYEE_OWNER on PAYEE_OWNER.OWNER_ID = PAYEE.PAYEE_NAME_ID

Hope this will clear what I really want.

Answer 1

You want something like this:

select col1,
       col2,
       (select colX
          from (select col1, colX from table2 order by colY desc) table2
         where table2.col1 = table1.col1
           and rownum < 2),
       (select colXX
          from (select col1, colXX from table3 order by colYY desc) table3
         where table3.col1 = table1.col1
           and rownum < 2)
  from table1;

or this:

select col1,
       col2,
       (select max(colX) keep(dense_rank last order by colY)
          from table2
         where table2.col1 = table1.col1),
       (select max(colXX) keep(dense_rank last order by colYY)
          from table2
         where table2.col1 = table1.col1)
  from table1;

This subselect

(select colX from table2 where table2.col1=table1.col1 and rownum<2 order by colY desc)

even if it worked would not return what you expect because rownum is calculated before order by. You would get random row from those which fulfill the condition table2.col1 = table1.col1 .

Try

select (SELECT max(OWNER_ADDRESS1) keep(dense_rank last order by nvl(oa.primary_addr, 'N'))
          FROM OWNER_ADDRESS OA, BANK_ACCOUNT
         WHERE PAYMENT.BANK_ACCOUNT_ID = BANK_ACCOUNT.BANK_ACCOUNT_ID
           and BANK_ACCOUNT.BANK_ID = OA.OWNER_ID) bank_address1,
       (SELECT max(OWNER_ADDRESS1) keep(dense_rank last order by nvl(oa.primary_addr, 'N'))
          FROM OWNER_ADDRESS OA
         WHERE OA.OWNER_ID = PAYEE_OWNER.OWNER_ID) payee_add1
  from PAYMENT
 inner JOIN PAYEE
    ON PAYMENT.PAYMENT_ID = PAYEE.PAYMENT_ID
 inner join OWNER PAYEE_OWNER
    on PAYEE_OWNER.OWNER_ID = PAYEE.PAYEE_NAME_ID

(I could have made some syntax errors, cannot check it).