title: An exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll but was not handled in user code. Cannot figure out issue
body: <p>I have tried using methods that others have used here to fix their issue but none of them are working for me. I am new to the ASP.NET framework and cannot understand why the information I am trying to send to my database isn't working. Also, Visual Studios isn't giving em an error until I try to submit the new data which makes it difficult for me to pinpoint the problem.</p>
  <pre><code>namespace ylena_exercise
  {
      public partial class KnockoutBind : System.Web.UI.Page
      {
          SqlConnection con = new SqlConnection(@&quot;Data Source=.\SQLEXPRESS;Initial Catalog=ylena_exercise;Integrated Security=True&quot;);
          protected void Page_Load(object sender, EventArgs e)
          {
              con.Open();
              GridView1.Visible = false;
          }
  
          protected void AddBtn_Click(object sender, EventArgs e)
          {
              SqlCommand cmd = new SqlCommand(&quot;insert into Customers ('&quot;+numid.Text+&quot;','&quot;+txtcustomer.Text+&quot;','&quot;+txtcontact.Text+&quot;','&quot;+txtaddress.Text+&quot;','&quot;+txtcity.Text+&quot;','&quot;+numpostcode.Text+&quot;','&quot;+txtcountry.Text+&quot;')&quot;,con);
              cmd.ExecuteNonQuery();
              con.Close();
              GridView1.DataBind();
              Label1.Visible = true;
              Label1.Text = &quot;Data Stored Successfully!&quot;;
              numid.Text = &quot;&quot;;
              txtcustomer.Text = &quot;&quot;;
              txtcontact.Text = &quot;&quot;;
              txtaddress.Text = &quot;&quot;;
              txtcity.Text = &quot;&quot;;
              numpostcode.Text = &quot;&quot;;
              txtcountry.Text = &quot;&quot;;                
          }
      }
  }
  </code></pre>
  <p><a href="https://i.stack.imgur.com/oZFQS.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oZFQS.png" alt="dbo.Customers data file" /></a></p>
  <p><a href="https://i.stack.imgur.com/54G6h.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/54G6h.png" alt="Message after clicking &quot;Submit&quot; button" /></a></p>
  <p>Is there something wrong with my data? Or perhaps the issue is ExecuteNonQuery?</p>