Mastering SqlConnection

Posted on: 2011-09-26

The SqlConnection object is an object that derive of DbConnection. It opens the connection between the application and the database. It's also inherit of IDisposable because of DbConnection.

var connection = new SqlConnection(); 
connection.ConnectionString = @"Data Source=PATRICK-PC\\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=True"; 
connection.Open(); 
connection.Close(); 

or

using (var connection = new SqlConnection()) { 
  connection.ConnectionString = @"Data Source=PATRICK-PC\\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=True"; 
  connection.Open(); 
  connection.Close(); 
} 

These two snippets of code illustrate the creation of a connection. Both of them were using connection string from a string but the value can be directly loaded from the app.config or web.config.

ConnectionStringSettings connectionStringSettings = ConfigurationManager.ConnectionStrings["ApplicationServices"]; 
using (var connection = new SqlConnection(connectionStringSettings.ConnectionString)) { 
  connection.Open(); 
  connection.Close(); 
} 

<configuration> 
  <connectionStrings> 
    <add name="ApplicationServices" connectionString="Data Source=PATRICK-PC\\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=True" providerName="System.Data.SqlClient" /> 
  </connectionStrings> 
... ...