title: Single declaration of connection string in form application
body: <p>In windows forms application there is no web.config. So how can i declare the single connection string? And how can I call it in another pages?</p>
  
  <p>In App.config page</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8" ?&gt;
      &lt;configuration&gt;
          &lt;connectionStrings&gt;
              &lt;add name="CONSTRING" connectionString="Data Source=SQL-PC;Initial Catalog=DATABASE;Integrated Security=True"/&gt;
          &lt;/connectionStrings&gt;
      &lt;/configuration&gt;
  </code></pre>
  
  <p>In Form I call this connectin string.</p>
  
  <pre><code>using System.Windows.Forms; 
  using System.Data.SqlClient; 
  using System.Configuration;
  
  namespace Sample {
      public partial class Sample: Form
      {
          public string conn = ConfigurationManager.ConnectionStrings["CONSTRING"].ConnectionString;
      }
  </code></pre>
  
  <p>Now there is error shows. <code>ConfigurationManager</code> does not exist in this current context. How can I solve it?</p>