para empezar lo puedes hacer desde tu web.config
Código:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.web>
<compilation defaultLanguage="c#" debug="true" />
</system.web>
<appSettings>
<add key="ConnectionInfo" value="server=(local);database=Northwind;Integrated Security=SSPI" />
</appSettings>
</configuration>
y en tu code lo llamas asi
Código HTML:
private void Page_Load(object sender, EventArgs e)
{
string connectionInfo = ConfigurationSettings.AppSettings["ConnectionInfo"];
using(SqlConnection connection = new SqlConnection(connectionInfo))
{
connection.Open();
perform work with connection
}
}