Question

Here is the example structure of the table:

ID    Name     ParentID
-----------------------
1     Ancestor      NULL
2     GrandFather   1
3     GrandMother   1
4     Child         3

I’m trying to write a query that would return

ID     Name        Family
----------------------------
 1     Ancestor 
 2     GrandFather Ancestor
 3     GrandMother Ancestor
 4     Child       Ancestor^GrandMother

The tricky part is that I want to show the family of all rows and in a top-down order.

If anyone can point me in the right direction, it would be appreciated 🙂

EDIT :: This is the real query, but it follows the same idea. it returns an error on line : marketparent.family + ‘^’+ t2.marketGroupName because it cant find marketparent

WITH marketparent ( marketGroupID,parentGroupID, marketGroupName,family)
AS
(
SELECT marketGroupID,
       parentGroupID,
       marketGroupName,
       '' as family 
 FROM EVE.dbo.invMarketGroups
 WHERE parentGroupID IS NULL
UNION ALL

    SELECT t2.parentGroupID,
     t2.marketGroupID,
     t2.marketGroupName,
     marketparent.family + '^'+ t2.marketGroupName
     FROM EVE.dbo.invMarketGroups as t2
     INNER JOIN marketparent as mp
     ON mp.marketGroupID = t2.parentGroupID
)

-- Statement using the CTE

SELECT TOP 10 *
FROM marketparent;

Answer 1

You did not specify your DBMS, so I’m assuming PostgreSQL

WITH RECURSIVE fam_tree (id, name, parent, family) as 
(
  SELECT id, 
         name, 
         parentid, 
         ''::text as family
  FROM the_unknown_table
  WHERE parent IS NULL

  UNION ALL

  SELECT t2.id, 
         t2.name, 
         t2.parentid, 
         fam_tree.family || '^' || t2.name
  FROM the_unknown_table t2 
     INNER JOIN fam_tree ON fam_tree.id = t2.parentid
)
SELECT *
FROM fam_tree;

This is standard SQL (except for the ::text typecast) that should work with very few changes on most modern DBMS.

Edit:

For SQL Server you would need to replace the standard concatention character with Microsoft’s non-standar + (and you need to remove the recursive keyword which is required by the standard but for some strange reason rejected by SQL Server)

WITH fam_tree (id, name, parent, family) as 
(
  SELECT id, 
         name, 
         parentid, 
         '' as family
  FROM the_unknown_table
  WHERE parent IS NULL

  UNION ALL

  SELECT t2.id, 
         t2.name, 
         t2.parentid, 
         fam_tree.family + '^' + t2.name
  FROM the_unknown_table t2 
     INNER JOIN fam_tree ON fam_tree.id = t2.parentid
)
SELECT *
FROM fam_tree;