SQL Query to concatenate column values from multiple rows in Oracle

Question

Would it be possible to construct SQL to concatenate column values from multiple rows?

The following is an example:

Table A

PID
A
B
C

Answer 1

In the select where you want your concatenation, call a SQL function.

For example:

select PID, dbo.MyConcat(PID)
   from TableA;

Then for the SQL function:

Function MyConcat(@PID varchar(10))
returns varchar(1000)
as
begin

declare @x varchar(1000);

select @x = isnull(@x +',', @x, @x +',') + Desc
  from TableB
    where PID = @PID;

return @x;

end

The Function Header syntax might be wrong, but the principle does work.