Concatenate items from different rows

Question

We are looking for an aggregate function similiar to the 'count' function, however instead of counting the distinct occurances, we want to concatenate them together into one single string.
i.e.
TestTable:
ID Name
1 A
1 B
1 C
2 A
2 F
SELECT ID, makestring(Name) FROM TestTable;
Produces:
1 ABC
2 AF
If possible please reply by e-mail to:
[email protected]
Any help with this is appreciated
Mark Emerson

Answer 1

Mark: I think this is not the best solution in performance, but it can help you like a beginning:
create or replace function makestring (v_id number) return varchar2
is
cursor c is select Name from TestTable
where id=v_id;
str varchar2(10):='';
begin
for r in c loop
str:=str | | r.Name;
end loop;
return str;
end;
You must use the DISTINCT clause, like this:
SELECT DISTINCT id, makestring(id) FROM TestTable;
This SELECT display the results that you are looking for. The main problem of this function is the size of the TestTable, and It will be important to consider create an index in the ID column, if doesn't exist yet (and to be sure of its use, using hints if it's necessary). Bye and good luck.