public class MyDatabaseConnection {
    public MyDatabaseConnection(string connectionString) {
        this.connectionString = connectionString;
        // create a database connection perhaps
    }
    // some methods for querying a database
    public void execute(string query) { }
}

在这种情况下，很容易添加第三个数据库连接

In this case it's easy to add a third database connection

MyDatabaseConnection con1 = new MyDatabaseConnection("Server=localhost");
MyDatabaseConnection con2 = new MyDatabaseConnection("Server=other_server");
MyDatabaseConnection con3 = new MyDatabaseConnection("Server=third_one");

并对每个

MyDatabaseConnection[] cons = new MyDatabaseConnection[]{ con1, con2, con3 };
foreach (MyDatabaseConnection con in cons) {
    con.execute(someSqlCommandText);
}