title: how to get values from sql database by selecting combobox items in c#
body: <p>I'm trying this coding , what is the error in this coding:</p>
  
  <pre><code>private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
          {
              SqlConnection con = new SqlConnection("Data Source =TWPL-PC\\SQLEXPRESS;Initial Catalog=TWPLSOFTWARE;Integrated security = True");
              con.Open();
              SqlCommand cmd = new SqlCommand("select ACC_ID ,ACC_TYPE ,ACC_ADD,ACC_CITY ,ACC_STATE ,ACC_COUNTRY ,ACC_TIN_N0 ,ACC_ECC_NO,ACC_RANGE,ACC_DIVISION ,ACC_COMMISS ,ACC_GST_NO ,ACC_CONTACT_PERSON ,ACC_PHONE_NO ,ACC_MOBILE_NO ,ACC_EMAIL ,ACC_PRICE_CODE ,ACC_APPROVAL_STATUS,ACC_PAN_NO from ACCOUNT where ACC_NAME='" + comboBox2.SelectedItem.ToString() + "'", con);
              cmd.Parameters.Add(new SqlParameter("@ACC_NAME", comboBox2.SelectedItem.ToString()));
              SqlDataReader dr = cmd.ExecuteReader();
              while (dr.Read())
              {
                  textBox17.Text = dr.GetString(0).ToString();
                  comboBox1.SelectedItem = dr.GetString(1).ToString();
                  richTextBox1.Text = dr.GetString(2).ToString();
                  textBox2.Text = dr.GetString(3).ToString();
                  textBox3.Text = dr.GetString(4).ToString();
                  textBox4.Text = dr.GetString(5).ToString();
                  textBox9.Text = dr.GetString(6).ToString();
                  textBox11.Text = dr.GetString(7).ToString();
                  textBox13.Text = dr.GetString(8).ToString();
                  textBox14.Text = dr.GetString(9).ToString();
                  textBox16.Text = dr.GetString(10).ToString();
                  textBox12.Text = dr.GetString(11).ToString();
                  textBox5.Text = dr.GetString(12).ToString();
                  textBox6.Text = dr.GetString(13).ToString();
                  textBox8.Text = dr.GetString(14).ToString();
                  textBox7.Text = dr.GetString(15).ToString();
                  textBox15.Text = dr.GetString(16).ToString();
                  //checkBox1.Checked=dr.GetString().ToString();
                  textBox10.Text = dr.GetString(18).ToString();
  
              }                     
  
          }
  </code></pre>
  
  <p>this is my problem : </p>
  
  <blockquote>
    <p>"The data types text and varchar are incompatible in the equal to
    operator."</p>
  </blockquote>