i m coding in c#.net. i am using service based database. i am getting an error while inserting a record. textbox1 is a varchar type :  private void button2_Click_1(object sender, EventArgs e)
        {
            SqlConnection cn = new SqlConnection(global::CFMSApp.Properties.Settings.Default.CFMSConnectionString);
            try
            {
                con.Open();
                SqlCommand cmd = con.CreateCommand();
                cmd.CommandType = CommandType.Text;
                cmd.CommandText = "insert into io values('" + textBox1.Text + "','" + textBox2.Text + "','" + textBox3.Text + "','" + textBox4.Text + "','" + textBox5.Text + "')";
                cmd.ExecuteNonQuery();
                con.Close();
                MessageBox.Show("adding new record done");
                textBox1.Text = " ";
                textBox2.Text = " ";
                textBox3.Text = " ";
                textBox4.Text = " ";
                textBox5.Text = " ";
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "error");
            }
            finally
            {
                cn.Close();
                con.Close();
            }