title: How to add and access connection string from web.config
body: <p>I want to add connection string to connect to mysql that are define in web.config file and access the same connection in my C# code how can I do this?</p>
  
  <p>Here is my code sample that run after onclick of a button to connect to database.</p>
  
  <pre><code>protected void Button2_Click(object sender, EventArgs e)
      {
          String a = DropDownList1.SelectedItem.Value;
          String b = DropDownList3.SelectedItem.Value.PadLeft(3, '0');      
          String c = TextBox2.Text.PadLeft(5,'0').ToString();
          String d = TextBox3.Text.ToString();
          String digit = a+ b  + c + d;
          try
          {
           myConn = new OdbcConnection("Driver={MySQL ODBC 3.51 Driver};Server=localhost;Database=testcase;User=root;Password=root;Option=3;");
           myConn.Open();
              //**
              string sql = "select * from testcase.main where reg_no =?";            
              //**
              OdbcCommand cmd = new OdbcCommand(sql, myConn);            
              //**
              cmd.Parameters.AddWithValue("?", digit);
              MyReader = cmd.ExecuteReader();
              //**
              while (MyReader.Read())
              {
                  String f = MyReader["pet_name"].ToString();
                  String g = MyReader["res_name"].ToString();
  
                  Label9.Visible = true;
                  Label9.Text = f;
  
                  Label10.Visible = true;
                  Label10.Text = "VS";
  
                  //Label11.Visible = true;
                  Label11.Text = g;
  
              }
  
              MyReader.Close();
          }
          catch (Exception e1)
          {
              Response.Write(e1.ToString());
          }
          finally
          {
              if (MyReader != null &amp;&amp; !MyReader.IsClosed)
              {
                  MyReader.Close();   
              }
  
              if (myConn != null &amp;&amp; myConn.State == ConnectionState.Open)
              {
                  myConn.Close();
              }
          }
  </code></pre>