Records are not updated in c sharp

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C#

Why records is not updating by the code given below ? No any error and exceptions are giving message also shown record updated but when i see in table the records are not updated why ?Please help me.

private void button3_Click(object sender, EventArgs e)
        {
            string sa = textBox1.Text.Trim();
            try
            {
                string connetionString = null;
                connetionString = "Data Source=JDPANDEY-PC;Initial Catalog=amsco;User ID = sa;Password= 123";
                cnn = new SqlConnection(connetionString);

                cnn.Open();

                ds = new DataSet();
                string sql = "select * from employee";
                da = new SqlDataAdapter(sql, cnn);
                da.Fill(ds, "employee");
                int r = 0;
                DataRow[] rs;
                rs = ds.Tables["employee"].Select("eid='" + textBox1.Text.Trim() + "'");
                r = rs.Length;
                if (r > 0)
                {
                    string str = "UPDATE employee set ename='" + textBox2.Text.Trim() + "',fname='" + textBox3.Text.Trim() + "' WHERE  eid ='" + textBox1.Text.Trim() + "'";
                    cmd = new SqlCommand(str, cnn);
                    cmd.ExecuteNonQuery();
                    MessageBox.Show("Record UPDATED");
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            cnn.Close();

        }