C#

class Program
{
    static void Main(string[] args)
    {
        // Create the connection.
        SqlConnection connection = new SqlConnection("YourConnectionString");

        // Pass it to class A as a parameter to the constructor.
        ClassA a = new ClassA(connection);
        a.DoStuff();

        // You can also pass it to class B as a parameter to a constructor.
        ClassB b = new ClassB(connection);
        b.DoStuff();

        // Or you could pass it to class C as a paramerter to a method.
        ClassC c = new ClassC();
        c.DoStuff(connection);

        // Or you could pass it to class D by setting a property.
        ClassD d = new ClassD();
        d.ConnectionForD = connection;
        d.DoStuff();
    }
}

public class ClassA
{
    private SqlConnection _sharedConnectionInA;

    public ClassA(SqlConnection connection)
    {
        _sharedConnectionInA = connection;
    }

    public void DoStuff()
    {
        _sharedConnectionInA.Open();
        // Do stuff
    }
}

public class ClassB
{
    private SqlConnection _sharedConnectionInB;

    public ClassB(SqlConnection connection)
    {
        _sharedConnectionInB = connection;
    }

    public void DoStuff()
    {
        _sharedConnectionInB.Open();
        // Do stuff
    }
}

public class ClassC
{
    public void DoStuff(SqlConnection connectionForC)
    {
        connectionForC.Open();
        // Do stuff
    }
}

public class ClassD
{
    private SqlConnection _sharedConnectionInD;

    public SqlConnection ConnectionForD
    {
        get
        {
            return _sharedConnectionInD;
        }
        set
        {
            _sharedConnectionInD = value;
        }
    }


    public void DoStuff()
    {
        _sharedConnectionInD.Open();
        // Do stuff
    }
}

public class X
{
    public readonly SqlCommand Command ;

    public X
    (
        string ConnectionString
    ) 
    {
        Command = ( new SqlConnection ( ConnectionString ) ).CreateCommand() ;
 
        return ;
    }
}

Matjaž Grahek wrote:

Where's the problem?