in c# global connection to be used in all classes

Question

I've a connection string saved to Properties.Settings.Default, i need to use an sql connection in all classes without having to declare it everytime, so how should it be declared?

Answer 1

You actually don't need to use a single SqlConnection everywhere. A better approach would be to create a class to manage you data access. Typically this is the duty of your Data Access Layer (DAL). DAL is a set of classes that handle all the database related stuff.

A very simple class for this purpose could be something like this:

public class DatabaseManager
{
    private static DatabaseManager _instance;
    private DatabaseManager()
    {
    }

    static DatabaseManager()
    {
        _instance = new DatabaseManager();
    }

    public DatabaseManager Instance
    {
        get { return _instance; }
    }

    private string GetConnectionString()
    {
        return Properties.Settings.Default.MyConnectionString;
    }

    public SqlConnection CreateConnection()
    {
        return new SqlConnection(GetConnectionString());
    }
}

You can extend this class to contain another methods to execute your queries.

I highly recommend you to use an ORM (Object-Relational Mapper) like Entity Framework.