How to use outer join on this query?

Question

Hi all,
Hope doing well,
sir i am having one query which is here
SELECT C.* ,
P.Comp_Name Parent
FROM Comp_Master C
LEFT JOIN Comp_Master P
ON C.Parent_ID = P.Comp_ID
WHERE C.Comp_ID = 5;
and here is my table Comp_Master data like this:
Comp_ID Parent_ID Comp_Name
5 1 abc123
1 ROOT abc@123
after running this query with all column value in parent column abc@123 value should come. but it's not happening.
could u check this.
if any query please let me know.
Thanks

Answer 1

p.s. when I run your query against your data....
SQL> ed
Wrote file afiedt.buf
  1  with comp_master as (select '5' comp_id, '1' parent_id, 'abc123' comp_name from dual union all
  2                       select '1' comp_id, 'ROOT' parent_id, 'abc@123' comp_name from dual
  3                      )
  4  --
  5  -- end of simulated table of test data
  6  --
  7  SELECT C.*
  8        ,P.Comp_Name Parent
  9  FROM Comp_Master C
10       LEFT JOIN Comp_Master P ON C.Parent_ID = P.Comp_ID
11* WHERE C.Comp_ID = 5
SQL> /
C PARE COMP_NA PARENT
5 1    abc123  abc@123I get the output I expect from that query.
So what are you expecting?
I just ran the equivalent in SQL Server (I can't believe you got me to go and run that piece of rubbish... I haven't touched it in ages)...
with comp_master as (select '5' comp_id, '1' parent_id, 'abc123' comp_name union all
                     select '1' comp_id, 'ROOT' parent_id, 'abc@123' comp_name
SELECT C.*
      ,P.Comp_Name Parent
FROM Comp_Master C
     LEFT JOIN Comp_Master P ON C.Parent_ID = P.Comp_ID
WHERE C.Comp_ID = 5... and it gave me the same output.