Reg: Fetching default value -

Question

Hi Experts,
Need some help in writing a query.
Table 'Tab_2' has column 'c3' which checks for its value from 'tab_1' column 'c1' values, and accordingly fetches value from column 'c2'.
But if a value from c3 is not present in tab_1 column 'c1', it should default 'c2' value as 'dx'.
Please find below the Create & Insert scripts:
create table tab_1(
    c1 varchar2(200Char),
    c2 varchar2(200Char)
create table tab_2(
    c3 varchar2(200Char),
    c4 varchar2(200Char)
insert into tab_1 values('104,113,146,165','1x');
insert into tab_1 values('204,213,246,265','2x');
insert into tab_1 values('304,313,346,365','3x');
insert into tab_1 values('default','dx');
commit;
insert into tab_2 values('146',null);
insert into tab_2 values('265',null);
insert into tab_2 values('333',null);
commit;Here's query where I'm stuck:
SQL> with x1 as
  2  (
  3      select
  4          REGEXP_SUBSTR(c1,'[^,]+',1,level) id1,
  5          c2
  6      from tab_1
  7          connect by level <= length(translate(c1,'~0123456789','~'))+1
  8          and prior c1 = c1
  9          and prior sys_guid() is not null
10          and c1 != 'default'
11  )
12  select
13      id1, c2, c3
14  from x1 RIGHT OUTER JOIN tab_2
15      on (x1.id1 = tab_2.c3);
ID1        C2         C3
146        1x         146
265        2x         265
                      333Please let me know if any further clarification is needed.
- Ranit

Answer 1

The data model looks flawed. So not sure the following solution will satisfy all the issues with respect to your problem.
with t
as
select regexp_substr(c1, '[^,]+', 1, level) c1
      , c2
   from tab_1
connect
     by level <= length(c1) - length(replace(c1, ',')) + 1
    and c1 = prior c1
    and prior dbms_random.value() is not null
select t1.c3, t2.c1, nvl2(t2.c1, t2.c2, (select c2 from tab_1 where c1 = 'default')) c2
  from tab_2 t1
  left join t t2
    on t1.c3 = t2.c1;Edited by: Karthick_Arp on May 22, 2013 12:39 AM
Changed NVL to NVL2