Question

I have to somehow group up rows while concatenating a certain column, I am not sure how I would go about doing this. The following is an example of what I need.

CREATE TABLE People(
PersonName varchar(100),
PersonAge int
)

INSERT INTO People
SELECT 'bill', 21

INSERT INTO People
SELECT 'harry', 21

INSERT INTO People
SELECT 'wesley', 21

INSERT INTO People
SELECT 'tom', 42

INSERT INTO People
SELECT 'paul', 42

INSERT INTO People
SELECT 'phil', 53

a normal select from this table will produce the following:

bill    21
harry   21
wesley  21
tom     42
paul    42
phil    53

what I need is the following:

bill, harry, wesley    21
tom,paul               42
phil                   53

I am not sure if this is possible but it would be really helpful if anyone know how to do it. Thanks in advance.

Answer 1

This is a difficult problem. For an in depth treatment of it see this excellent post:

http://www.simple-talk.com/sql/t-sql-programming/concatenating-row-values-in-transact-sql/

For a simple solution, I used a cursor, it does the job:

create procedure
doIt
as

create table #out
(people varchar(2000) null, -- assumed max length of concatenated string
age int)

insert into #out(age)
select distinct personAge from people

declare @str varchar(2000)
select @str = isnull(@str,'') + personname +',' from people

declare @age int
declare cur cursor for select age from #out

open cur
fetch next from cur into @age

while @@fetch_status =0
begin 
    set @str = ''
    select @str = isnull(@str,'') + personname +',' from people where personage = @age
    update #out set people = left(@str,len(@str)-1) where age=@age
    fetch next from cur into @age   
end

close cur
deallocate cur

select * from #out