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> ... ...