Question

I have a query which returns the custref having multiple tetranumbers(1 to n mapping)

select *
  from cdsheader
 where custref in(select custref
                    from(select *
                           from cdsheader h,custandaddr c
                          where h.custref = c.cwdocid
                            and c.addresstype = 'C')
                   group by custref
                  having count(distinct( tetranumber )) > 1) 

count 5144

My objective is to pull the matching address details along with the above result, but I guess I am missing something here.

Something like…

select a.cworderid,a.cwcreated,a.organisationtype,a.custref,a.tetranumber,
       b.buildingname,b.streetname,b.posttown,b.postcode,b.country
  from cdsheader a,custandaddr b
 where custref in (select custref
                     from cdsheader h,custandaddr c
                    where h.custref = c.cwdocid
                      and c.addresstype = 'C')
                    group by custref
                   having count(distinct( tetranumber )) > 1)
 order by a.custref,a.tetranumber,a.cworderid; 

Answer 1

Rather than scanning your table twice ,create a inline view and fetch the result using analytical function .Please test

SELECT     inner.cworderid,
           inner.cwcreated,
           inner.organisationtype,
           inner.custref,
           inner.tetranumber,
           inner.buildingname,
           inner.streetname,
           inner.posttown,
           inner.postcode,
           inner.country
FROM(           
  SELECT   h.cworderid,
           h.cwcreated,
           h.organisationtype,
           h.custref,
           h.tetranumber,
           c.buildingname,
           c.streetname,
           c.posttown,
           c.postcode,
           c.country,
           COUNT(DISTINCT tetranumber) OVER(PARTITION BY h.custref) cnt
    FROM   cdsheader h, custandaddr c
    WHERE  h.custref = c.cwdocid 
       AND c.addresstype = 'C'
      )inner
  WHERE inner.cnt>1 
 ORDER BY inner.custref, inner.tetranumber, inner.cworderid;