title: Sql server express and connection string in web.config
body: <p>i have connection string stored in web.config file but it is giving me the error.</p>
  
  <pre><code>&lt;connectionStrings&gt;
  &lt;add name="ConnectionString" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\DbProduct.mdf;Integrated Security=True;User Instance=True"
  providerName="System.Data.SqlClient" /&gt;
  </code></pre>
  
  <p></p>
  
  <p>where is the bug in the connection string. i have stored my db DbProduct.mdf in app_data folder. i have never use SQLEXPRESS. so i need guide line. thanks</p>