I would like to create a function that returns a concatinated string of a given field of given query. Here is what I did. And this one gives me an error. Must declare the table variable "@qry".

CREATE FUNCTION dbo.testing 
    ( 
    @qry varchar(1000),
    @fld varchar(100),
    @separator varchar(15) = '; '
    )
RETURNS  varchar
AS
    BEGIN
    DECLARE @rslt varchar(1000)
    SET @rslt ='' 

     SELECT @rslt = @rslt + @separator + CAST(@fld as varchar(160)) FROM  @qry

    RETURN @rslt
    END

What I am trying to do is pass a query to this function and receive a concatinated string for certain field of the query.
Is this possible?
What am I doing wrong?
EDIT: BTW I have MSSQL Server 2005;