Question

I am having problem in framing one sql query.
I need to select all records based on Transaction ID as I explained below

1. Assume user given transaction TX444, I need to fetch all records with Child Id = Parent Id of given transaction AND Parent_Id = Child_Id of already selected records.

So if I give TRansaction as TX444, all records shown should be selected.

1. Assume user given Transaction = TX234, then I need to fetch all records with Child Id = Parent Id of given transaction AND Parent_Id = Child_Id of already selected records.
   in this case last record will not be included.

I am trying to write SELECT query. But nothing is working 🙁

PARENT_ID       CHILD_ID                   TRANSACTION        STATE
1               4                           TX123           PF
2               4                           TX128           PS
3               5                           TX230           FF
4               5                           TX234           FS
5               0                           TX444           DS

I am not SQL person, but I need to make this up

Answer 1

In Oracle you can use CONNECT BY to recursively loop through rows:

SELECT  Parent_ID, 
        Child_ID, 
        Transaction, 
        State,
        CASE Level WHEN 1 THEN 'Selected' ELSE 'Child' END AS Relation
FROM    Transactions
START WITH Transaction = 'TX444'
CONNECT BY PRIOR Child_ID = Parent_ID
UNION
SELECT  Parent_ID, 
        Child_ID, 
        Transaction, 
        State,
        CASE Level WHEN 1 THEN 'Selected' ELSE 'Parent' END AS Relation
FROM    Transactions
START WITH Transaction = 'TX444'
CONNECT BY PRIOR Parent_ID = Child_ID;

I’ve put an example on SQL Fiddle, but I’ve used slightly different children/parents to your data to fully show how you can use CONNECT BY not just to get the parents/children, but also to determine what generation each is.