Multiple recursive union all selects in a CTE SQL query

Question

I am trying to build a query for searching all parent and children rows from a table using a CTE query.

I can either search for parents and return children or search for children and return parents but I can not handle both possibilities in the one query.

I can only complete one of the UNION ALL queries.

Where am I going wrong?

declare @search nvarchar(50)

--set @search = '%Nucleus sub project%';
set @search = '%Nucleus test';

WITH Parent AS
(
    SELECT * 
    FROM tblProjects 
    WHERE ProjNo LIKE @search 
       OR ProjDes LIKE @search

    UNION ALL

    SELECT tblProjects.* 
    FROM tblProjects  
    JOIN Parent ON tblProjects.proID = Parent.ParentProjID

    UNION ALL

    SELECT tblProjects.* 
    FROM tblProjects  
    JOIN Parent ON tblProjects.ParentProjID = Parent.proID 
)
SELECT distinct * 
FROM Parent 
ORDER BY ParentProjID

I get an error :

The statement terminated. The maximum recursion 100 has been exhausted before statement completion.

Answer 1

Try using two different CTEs:

WITH x AS (
    SELECT p.*
    FROM tblProjects p
    WHERE  ProjNo LIKE @search OR ProjDes LIKE @search
   ),
   parents as (
    SELECT * 
    FROM x 
    UNION ALL
    SELECT p.* 
    FROM parents JOIN
         tblProjects p
         ON p.parentid= parents.proID
   ),
   children as (
    SELECT * 
    FROM x 
    UNION ALL
    SELECT p.* 
    FROM children JOIN
         tblProjects p
         ON children.parentid = p.proID
   )
SELECT distinct * 
FROM parents
UNION
SELECT distinct *
FROM children;