A complex join . Please help

Question

I have a complex join to perform.
I need some help please.
I have a table call Table A
TableA
id_entity    inst_type     inst_code  dt_trade
AGL          SE              5660249    01 Feb '06
AGL          SE              5660249    01 Feb '06
AGL          SE              5660249    05 Feb '06
TableB
id_inst                 id_inst_xref
0029010          SE     5660249
0070789          SE     5660249
0071190          SE     5660249
0072385          SE     5660249
0073215          SE     5660249
0084797          SE     5660249
0091375          SE     5660249
Table C
id_inst     id_isin
0029010     FR0000120172
0070789         FR0000120172
0071190     FR0000120172
*** All the id_inst in TableC have the same id_isinAll the 3 Tables now have to be linked to together such that
Output
id_entity    Inst_code   id_isin         dt_trade    count
AGL          5660249     FR0000120172    01 Feb '06  2
AGL          5660249     FR0000120172    02 Feb '06  1What I am doing is
Select ta.id_entity,ta.id_inst_code,ta.dt_trade,tc.id_isin,count(*)
from  TableA ta,TableB tb,TableC tc
where ta.id_entity = 'AGL'    and
      ta.inst_code       = (How do I get the id_inst from TableB)
                            and then use the id_inst from TableB
                            to get the id_isin from TableC)
group by ta.id_entity,ta.id_inst_code,ta.dt_trade,tc.id_isin
Can I say :
Select ta.id_entity,ta.id_inst_code,ta.dt_trade,tc.id_isin,count(*)
from  TableA ta,TableB tb,TableC tc
where ta.id_entity = 'AGL'    and
      ta.inst_code = (Select distinct tb.id_inst
                      from tableB tb
                      where tb.id_inst_xref = ta.id_inst_code
                      ) and then link the id_inst from here to TableC ang get the id_isin??Can someone please help.??

Answer 1

I had a bit of a go at writing the query but I don't quite understand the data. Here is what I tried.
jeff@ORA10GR2> create table tablea
2 (id_entity varchar2(3)
3 ,inst_type varchar2(3)
4 ,inst_code number
5 ,dt_trade date);
Table created.
jeff@ORA10GR2>
jeff@ORA10GR2> insert into tablea values ('AGL', 'SE', 5660249, to_date('20060201','YYYYMMDD'));
1 row created.
jeff@ORA10GR2> insert into tablea values ('AGL', 'SE', 5660249, to_date('20060201','YYYYMMDD'));
1 row created.
jeff@ORA10GR2> insert into tablea values ('AGL', 'SE', 5660249, to_date('20060205','YYYYMMDD'));
1 row created.
jeff@ORA10GR2>
jeff@ORA10GR2> create table tableb
2 (id_inst number
3 ,inst_type varchar2(3)
4 ,id_inst_xref number);
Table created.
jeff@ORA10GR2>
jeff@ORA10GR2> insert into tableb values (0029010, 'SE', 5660249);
1 row created.
jeff@ORA10GR2> insert into tableb values (0070789, 'SE', 5660249);
1 row created.
jeff@ORA10GR2> insert into tableb values (0071190, 'SE', 5660249);
1 row created.
jeff@ORA10GR2> insert into tableb values (0072385, 'SE', 5660249);
1 row created.
jeff@ORA10GR2> insert into tableb values (0073215, 'SE', 5660249);
1 row created.
jeff@ORA10GR2> insert into tableb values (0084797, 'SE', 5660249);
1 row created.
jeff@ORA10GR2> insert into tableb values (0091375, 'SE', 5660249);
1 row created.
jeff@ORA10GR2>
jeff@ORA10GR2> create table tablec
2 (id_inst number
3 ,id_isin varchar2(20)
4 );
Table created.
jeff@ORA10GR2>
jeff@ORA10GR2> insert into tablec values (0029010, 'FR0000120172');
1 row created.
jeff@ORA10GR2> insert into tablec values (0070789, 'FR0000120172');
1 row created.
jeff@ORA10GR2> insert into tablec values (0071190, 'FR0000120172');
1 row created.
jeff@ORA10GR2>
jeff@ORA10GR2>      select tb.id_inst_xref, tc.id_isin
2      from tableb tb, tablec tc
3      where tb.id_inst = tc.id_inst;
ID_INST_XREF ID_ISIN
5660249 FR0000120172
5660249 FR0000120172
5660249 FR0000120172
jeff@ORA10GR2>
jeff@ORA10GR2> select ta.id_entity,ta.inst_code,ta.dt_trade,dt.id_isin,count(*)
2 from tablea ta,
3      (select tb.id_inst_xref, tc.id_isin
4      from tableb tb, tablec tc
5      where tb.id_inst = tc.id_inst) dt
6 where ta.inst_code = dt.id_inst_xref
7 group by ta.id_entity,ta.inst_code,ta.dt_trade,dt.id_isin;
ID_ INST_CODE DT_TRADE ID_ISIN COUNT(*)
AGL 5660249 05/FEB/06 FR0000120172 3
AGL 5660249 01/FEB/06 FR0000120172 6
jeff@ORA10GR2>
jeff@ORA10GR2> drop table tablea;
Table dropped.
jeff@ORA10GR2> drop table tableb;
Table dropped.
jeff@ORA10GR2> drop table tablec;
Table dropped.
jeff@ORA10GR2>
jeff@ORA10GR2> spool off