Select of a child table return double number of rows than it should

Hi,

I have this code:

                 string prname = Console.ReadLine();

                SqlDataAdapter spjadap =  new SqlDataAdapter("select * from spj", connString);
                spjadap.Fill(ds, "tab");
                DataColumn parentcol = ds.Tables["j"].Columns["j#"];

                DataColumn childcol = ds.Tables["tab"].Columns["j#"];
                DataRelation dr = new DataRelation("tab_j", parentcol, childcol);

                ds.Relations.Add(dr);

                DataTable spjtable1 = ds.Tables["tab"];
                DataRow[] rows = spjtable1.Select("Parent.jname = '" + prname + "'");
                if (rows.Length == 0)
                {
                    Console.WriteLine(something);
                }
                foreach (DataRow row in rows)

                { Console.WriteLine(@"for " + prname + " are: P# = " + row["p#"]); }

but instead of supposed, expected number of rows, it reurns double number of rows.

Can anybody help me please where is my mistake?

Thanks