How to update table from multiple rows of a datagridview. My code works but only updates the last line of my datagridview not all lines.

// this is helping code to please check.

class CodeProject_Solution
    {
        SqlConnection con = new SqlConnection("your constring");
        SqlCommand cmd = new SqlCommand("select * form CoursesLines");
        DataTable dtTemp = new DataTable();

        private void UpdateSolution()
        {
            //open connection
            con.Open();
            cmd.Connection = con;

            SqlDataAdapter adapter = new SqlDataAdapter(cmd);
            SqlCommandBuilder builder = new SqlCommandBuilder(adapter);
            builder.ConflictOption = ConflictOption.OverwriteChanges;//to insert update and delete data and also update dtTemp            

            adapter.Fill(dtTemp);
        }

        private void AddMultiValues()
        {
            for (int i = 0; i < 50; i++)
            {
                DataRow dr = dtTemp.NewRow();
                dr["FId"] = "id" + i;
                dr["CoursID"] = "CoursID" + i;
                dr["CoursDescr"] = "CoursDescr" + i;
                dtTemp.Rows.Add(dr);
            }
            dtTemp.AcceptChanges();
            //know call function
            UpdateSolution();
            //know all 50 rows will be inserted in db. and also update DataTable and CoursesLines(in database)
        }
    }