While using MSSQL Server with .Net Framework, to connect with database use these simple steps.
In Web.Config File (Using LocalDb) :
<connectionStrings>
<add name="OnlineTicketingSystem" connectionString="Data Source=(LocalDb)\MSSQLLocalDB;Initial Catalog=OnlineTicketingSystemDB;Integrated Security=SSPI;" providerName="System.Data.SqlClient"/>
</connectionStrings>
In Web.Config File (Using Local) :
<connectionStrings>
<add name="OnlineTicketingSystem" connectionString="Data Source=(Local);Initial Catalog=OnlineTicketingSystemDB;Integrated Security=SSPI;" providerName="System.Data.SqlClient"/>
</connectionStrings>
In DbContext :
public OnlineTicketingSystemContext() : base("OnlineTicketingSystem")
{}