MS SQL Hierarchy Concatenate all descendants into single value

Question

I have Googled / searched here for hours and cannot find anything that seems to end up with the result I desire, despite my best efforts.

I can't actually find an easy way to explain what I'm after so please consider the following example data:

Section_T

    SectionId   SectionParentId     S_Start S_End
    1           NULL                <A>     </A>
    2           NULL                <B>     </B>
    3           NULL                <C>     </C>
    4           NULL                <D>     </D>
    5           4                   <E>     </E>
    6           4                   <F>     </F>
    7           4                   <G>     </G>
    8           4                   <H>     </H>
    9           8                   <I>     </I>
    10          2                   <J>     </J>

and wish to get the following result:

Section
<A></A>
<B><J></J></B>
<C></C>
<D><E></E><F></F><G></G><H><I></I></H></D>

XML PATH doesn't seem to work for this scenario due to the HTML tag like data, which must stay.

The real data is a lot more complicated, but finding a solution to this, will point me in the right direction, and then I can go from there, as I'd rather figure out as much as I can on my own.

Answer 1

You need to create recursive SQL function like below :

CREATE FUNCTION getSubNodes (@SectionId INT)
RETURNS VARCHAR(MAX)
AS
BEGIN
    DECLARE @SubNodes VARCHAR(MAX)
    SET @SubNodes = ''

    IF EXISTS(SELECT SectionId FROM Section_T WHERE SectionParentId = @SectionId)
    BEGIN
          SELECT   @SubNodes = COALESCE(@SubNodes + '','') + 
                   S_Start + dbo.getSubNodes(SectionId) + S_End 
          FROM Section_T 
          WHERE SectionParentId = @SectionId
          ORDER BY SectionOrder
    END

    RETURN @SubNodes
END

and you can use that function like below :

SELECT  S_Start + dbo.getSubNodes(SectionId) + S_End 
FROM Section_T
WHERE SectionParentId IS NULL