Error - "UNION operator must have an equal number of expressions" when using CTE for recursive selection

Question

At this moment I have a table tblLocation with columns ID, Location, PartOfID.

The table is recursively connected to itself: PartOfID -> ID

My goal is to have a select output as followed:

> France > Paris > AnyCity >

Explanation: AnyCity is located in Paris, Paris is located in France.

My solution that I found until now was this:

; with q as (
select ID,Location,PartOf_LOC_id from tblLocatie t
where t.ID = 1 -- 1 represents an example
union all
select t.Location + '>' from tblLocation t
inner join q parent on parent.ID = t.LOC_PartOf_ID
)
select * from q

Unfortunately I get the following error:

All queries combined using a UNION, INTERSECT or EXCEPT operator must have an equal number of expressions in their target lists.

If you have any idea how I could fix my output it would be great.

Answer 1

The problem lays here:

--This result set has 3 columns
select LOC_id,LOC_locatie,LOC_deelVan_LOC_id from tblLocatie t
where t.LOC_id = 1 -- 1 represents an example

union all

--This result set has 1 columns   
select t.LOC_locatie + '>' from tblLocatie t
inner join q parent on parent.LOC_id = t.LOC_deelVan_LOC_id

In order to use union or union all number of columns and their types should be identical cross all result sets.

I guess you should just add the column LOC_deelVan_LOC_id to your second result set