What is a efficient SQL for this query ?

Question

Hi,
I am using 9.2 database. Suppose I am having following 2 tables
Table p having only one column i.e. 'a'. Values in this column are
a1
b1
c1
d1
Table Q having three columns a, b, c
a1, 1, 100
a1, 2, 50
b1, 1, 30
b1, 2, 40
d1, 2, 90
Table Q can be joined only using column a.
Table Q can have multiple or no records for column a in table p. Based on above sample data, I want following output
a1, 100, 50
b1, 30, 40
c1
d1, 90
Kindly tell be how can I achive this in most efiicient way !!!
thanks & regards
PJP

Answer 1

I only have you two tracks about how do it.
If you want all the columns from p with or wihout q you have to do:
11:35:58 SQL> l
1 select p.*, q.*
2 from p,q
3* where p.a = q.a (+)
11:37:27 SQL> /
For change the order of the colums for rows you can see the url, the are more examples like that only need to search "columns for rows" in this forums.
Anyway:
with rt as
select 'a1' a, 1 b, 100 c from dual union
select 'a1', 2, 50 from dual union
select 'b1', 1, 30 from dual union
select 'b1', 2, 40 from dual union
select 'd1', 2, 90 from dual)
--select * from rt
select a, decode('1','0','0',rtrim(xmlagg(xmlelement(b, b || ',')).extract('//text()'),',')) b
, decode('1','0','0',rtrim(xmlagg(xmlelement(c, c || ',')).extract('//text()'),','))
from rt
group by a
Message was edited by:
cth
Other way:
select a, ltrim(b,',') as b, ltrim(c,',') as c
from (
select row_number() over (partition by a order by length(b) desc) as rn, a, b,c
from (select a, sys_connect_by_path(b, ',') as b,
          sys_connect_by_path(c, ',') as c
from (
select row_number() over (partition by a order by b) as rn, a, b,c
from rt) y
connect by rn = prior rn + 1 and prior a = a
start with rn = 1
where rn = 1
Message was edited by:
cth