使用oracle在一个表中基于最大值联接三个表

Question

I have a question for joining tables. I have three tables. In table 2 there are different value to same ID and i need to retrieve row based on higher value. Kindly help me. Am new to this concept. Till now I have tried

select a.trefno, a.tstatusno, max(b.tstatusno), b.trefno, distinct c.trefno, c.status
from Table1 a
inner join Table3 c on a.trefno = c.TREFNO
inner join Table2 b on c.trefno = b.TREFNO
where b.tstatusno = (select max(tstatsno) from Table2 t where b.tref = t.trefno group by t.trefno)
group by a.trefno

These is the three table samples i have shown

I want to join all three table with tref as unique id and max(tstatusno) from table 2.

Answer 1

You can use window functions:

select a.trefno, a.tstatusno, b.tstatusno, b.trefno, c.trefno, c.status
from Table1 a inner join
     Table3 c
     on a.trefno = c.TREFNO inner join
     (select b.*,
             row_number() over (partition by b.trefno order by b.statusno desc) as seqnum
      from Table2 b
     ) b 
     on c.trefno = b.TREFNO and b.seqnum = 1