How to “Implode” (de-normalize/concat) multiple columns into a single column?

Question

I have a query which outputs something like this:

+-------+----+--------------+
| F_KEY | EV | OTHER_COLUMN |
+-------+----+--------------+
| 100   | 1  | ..         


        

Answer 1

here is the best concatenation method, it will not expand special characters like other XML methods:

--Concatenation with FOR XML & eliminating control/encoded char expansion "& < >"
set nocount on;
declare @YourTable table (RowID int, HeaderValue int, ChildValue varchar(5))
insert into @YourTable VALUES (1,1,'CCC')
insert into @YourTable VALUES (2,2,'B<&>B')
insert into @YourTable VALUES (3,2,'AAA')
insert into @YourTable VALUES (4,3,'
')
insert into @YourTable VALUES (5,3,'A & Z')
set nocount off
SELECT
    t1.HeaderValue
        ,STUFF(
                   (SELECT
                        ', ' + t2.ChildValue
                        FROM @YourTable t2
                        WHERE t1.HeaderValue=t2.HeaderValue
                        ORDER BY t2.ChildValue
                        FOR XML PATH(''), TYPE
                   ).value('.','varchar(max)')
                   ,1,2, ''
              ) AS ChildValues
    FROM @YourTable t1
    GROUP BY t1.HeaderValue

OUTPUT:

HeaderValue ChildValues
----------- ---------------
1           CCC
2           AAA, B<&>B
3           
, A & Z

(3 row(s) affected)