从不同列中的多个表中获取值

Question

I need to fetch data from multiple tables but with some scenarios here are test scripts to re-create the problem

create table sub_test (sub_id number);

create table sub_svc_test (sub_id number, sub_svc_id number);

create table sub_svc_parm_test (sub_svc_id number, parm_id number, val varchar2(20) );

insert into sub_test values (100);
insert into sub_test values (101);
insert into sub_test values (102);

insert into sub_svc_test values (100,1001);
insert into sub_svc_test values (100,1002);
insert into sub_svc_test values (101,1005);
insert into sub_svc_test values (101,1006);
insert into sub_svc_test values (101,1007);
insert into sub_svc_test values (102,1009);
insert into sub_svc_test values (102,1010);

insert into sub_svc_parm_test values (1001, 51, 'test_id');
insert into sub_svc_parm_test values (1001, 53, 'no');
insert into sub_svc_parm_test values (1002, 54, 'max');
insert into sub_svc_parm_test values (1005, 51, 'test_id');
insert into sub_svc_parm_test values (1007, 51, 'test_id');
insert into sub_svc_parm_test values (1007, 54, 'min');

I need to fetch values from sub_svc_parm_test table for VAL column for a particular parm_id such that

select * from sub_svc_test ss, sub_svc_parm_test ssp
where ss.sub_svc_id = ssp.sub_svc_id and parm_id = 51;

this query will give me the VAL for 51 parm_id now i need to craete a view which will show me the VAL for parm_id 51, 54 but in differnet column like

select ssp.val, ssp1.val
from sub_svc_test ss, sub_svc_parm_test ssp, sub_svc_test ss1,
     sub_svc_parm_test ssp1
where ss.sub_svc_id = ssp.sub_svc_id
  and ssp.parm_id = 51
  and ssp1.parm_id  = 54
  and ss1.sub_svc_id = ssp1.sub_svc_id;

This query will give me output but also it performs cross joins as i have not join the sub_svc_test ss, and sub_svc_test ss1 so it gives me 6 rows 2*3 but the requirement is that it should show me MAX rows of any column in our case it is first column (3 rows) and the remaining row which do not have data can contain any string or simply null in it like

VAL             VAL_1
--------------     -------------             
test_id         max
test_id         min
test_id         null

i am using ---- Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production

Please ask for any clarification

Thanks

Answer 1

So you actually want to perform two separate selects and display them next to each other.

Maybe something like this could work:

select val, val1 from (
  (select rownum as r, val as val from sub_svc_parm_test ssp1 where parm_id = 51) 
  full outer join 
  (select rownum as r1, val as val1 from sub_svc_parm_test ssp2 where parm_id = 54)
  on r = r1
)