Different conditions for different columns

Question

Hi,
I have two tables and both have 3 common columns. I have to write a query joining the two tables and get different columns with different conditions.
For e.g., I have the tables test and test1.
create table test (a1 varchar(10), a2 varchar(10), a3 varchar(10), a4 date, a5 number, a6 number, a7 number, a8 number);
create table test1 (a1 varchar(10), a2 varchar(10), a3 varchar(10));
insert into test1 values('abc', 'a', 'z');
insert into test1 values('xyz', 'b', 'y');
insert into test values('abc', 'a', 'x', trunc(sysdate,'MM'), 100, 200, 300, 400);
insert into test values('abc', 'b', 'z', trunc(sysdate,'MM'), 567, 4778, 4234, 6767);
insert into test values('xyz', 'a', 'y', trunc(sysdate,'MM'), 5467, 2134, 5678, 8332);
insert into test values('xyz', 'b', 'z', trunc(sysdate,'MM'), 3534, 744, 678547, 46);
insert into test values('abc', 'a', 'x', trunc(add_months(sysdate,-1),'MM'), 700, 800, 900, 600);
insert into test values('abc', 'b', 'z', trunc(add_months(sysdate,-1),'MM'), 565477, 474578, 4456234, 226767);
insert into test values('xyz', 'a', 'y', trunc(add_months(sysdate,-1),'MM'), 235467, 2342134, 255678, 258332);
insert into test values('xyz', 'b', 'z', trunc(add_months(sysdate,-1),'MM'), 324534, 25744, 678547, 78846);
select * from test1;
A1     A2     A3
abc     a     z
xyz     b     y
select * from test;
A1     A2     A3     A4                     A5     A6     A7     A8
abc     a     x     05/01/2010 00:00:00     100     200     300     400
abc     b     z     05/01/2010 00:00:00     567     4,778     4,234     6,767
xyz     a     y     05/01/2010 00:00:00     5,467     2,134     5,678     8,332
xyz     b     z     05/01/2010 00:00:00     3,534     744     678,547     46
abc     a     x     04/01/2010 00:00:00     700     800     900     600
abc     b     z     04/01/2010 00:00:00     565,477     474,578     4,456,234     226,767
xyz     a     y     04/01/2010 00:00:00     235,467     2,342,134     255,678     258,332
xyz     b     z     04/01/2010 00:00:00     324,534     25,744     678,547     78,846I have to write a query to get values for columns a1, a4, a5, a6, a7 and a8. For each distinct month fro mthe column a4, the values for columns a1, a4 a5 and a6 should be based on the condition test1.a1=test.a1 and test1.a2=test.a2. The condition for columns a7 and a8 should be test1.a1=test.a1 and test1.a3=test.a3.
How can I do this?
Thanks,
Machaan

Answer 1

remove the 4th join and only duplicate test;
SQL> ed
Wrote file afiedt.buf
  1  select distinct
  2  case
  3          when t11a1 is null then
  4            t12a1
  5          else
  6            t11a1
  7        end as a1
  8        ,case
  9          when t11a4 is null then
10            t12a4
11          else
12            t11a4
13         end as a4
14        ,case
15          when t11a5 is null then
16            t12a5
17          else
18            t11a5
19         end as a5
20  from (
21        select t11.a1 as t11a1
22              ,t11.a2 as t11a2
23              ,t11.a3 as t11a3
24              ,t11.a4 as t11a4
25              ,t11.a5 as t11a5
26              ,t11.a6 as t11a6
27              ,t11.a7 as t11a7
28              ,t11.a8 as t11a8
29              ,t12.a1 as t12a1
30              ,t12.a2 as t12a2
31              ,t12.a3 as t12a3
32              ,t12.a4 as t12a4
33              ,t12.a5 as t12a5
34              ,t12.a6 as t12a6
35              ,t12.a7 as t12a7
36              ,t12.a8 as t12a8
37        from test1 t1
38            ,test  t11
39            ,test  t12
40        where t1.a1 = t11.a1
41        and   t1.a2 = t11.a2
42        and   t1.a3 = t12.a3
43* )
SQL>
SQL> /
A1         A4                A5
xyz        01-APR-10     324534
xyz        01-MAY-10       3534
abc        01-APR-10        700
abc        01-MAY-10        100