Related to Join

Question

I have 2 tables and i am trying to join them
SQL> select * from t_tldn_allocated ;
ID TLDN_FROM TLDN_TO QTY MSC_ID PURPOSE_ID
165 9370682000 9370682249 250 160 1
171 9336798000 9336798249 250 160 1
177 9351029000 9351029249 250 160 1
183 9337912000 9337912249 250 160 1
189 9341520000 9341520249 250 160 1
195 9351030000 9351030999 1000 160 1
201 9332712000 9332712249 250 160 1
7 rows selected.
SQL> select * from t_trn_allocated;
ID TRN_FROM TRN_TO QTY MSC_ID
139 9370393000 9370393999 1000 160
SQL> select a.TLDN_FROM,a.TLDN_TO,b.TRN_FROM,b.TRN_TO from t_tldn_allocated a join t_trn_allocated b on a.msc_id=b.msc_id;
TLDN_FROM TLDN_TO TRN_FROM TRN_TO
9370682000 9370682249 9370393000 9370393999
9336798000 9336798249 9370393000 9370393999
9351029000 9351029249 9370393000 9370393999
9337912000 9337912249 9370393000 9370393999
9341520000 9341520249 9370393000 9370393999
9351030000 9351030999 9370393000 9370393999
9332712000 9332712249 9370393000 9370393999
but the TRN_FROM and TRN_TO are getting repeated i dont want the duplicates but only single and for rest of the rows i want the values to be 0 can any one provide me a query to do so Thanks in advance

Answer 1

You can use decode to do this:
select a.tldn_from
      ,a.tldn_to
      ,decode(rownum,1,b.trn_from,0)
      ,decode(rownum,1,b.trn_to,0)
  from t_tldn_allocated a
  join t_trn_allocated b on a.msc_id = b.msc_id;The decode returns for the first row (rownum=1) the value from table b, for all other rows it returns 0.
Rene