There doesn't seem anything wrong with your connection string other than the 'Initial Catalog' missing from it. You have specified it as Database, but in a connection string, we specify it as Initial Catalog. So, re-write your connection string as below and try again:
<connectionStrings>
<add name="Dbconnection" connectionString="Server=localhost;Initial Catalog=OnlineShopping;Integrated Security=True"/>
</connectionStrings >
For detailed information, you can visit
http://msdn.microsoft.com/en-us/library/ms178411.aspx[
^] as well.