C# – How to Choose a Good Namespace Name?

It looks like you are having a design issue here: Tables should not extend the Database Abstraction Layer. Instead the DAL should be injected into the table as a dependency.

abstract class Table {
    protected $dal;

    public function __construct(DAL $dal) {
        $this->dal = $dal;
    }

    // whatever else all tables have in common
}

class Table_User extends Table {
    public function someMethod() {
        $this->dal->someOtherMethod();
    }
}

$table = new MyTable($dal);
$table->someMethod();

That way you will create a DAL at some upper scope and pass it down. This will also allow you to use multiple different database engines at the same time.

Additionally you obviously should not create your tables directly in your controller but let a specialized class do that. For example you could use a factory:

class TableFactory {
    protected $dal;

    public function __construct(DAL $dal) {
        $this->dal = $dal;
    }

    public function createTable($name) {
        $className = 'Table_' . $name;
        return new $className($this->dal);
    }
}

That way you can create a table factory at some point with an injected DAL and pass that table factory around.

$table = $factory->createTable('User');

You're right that you shouldn't name the namespace the same as a type it contains. I think there are several approaches you can use:

• Pluralize: Model.DataSources.DataSource

  This works especially well if the primary purpose of the namespace is to contain types that inherit from the same base type or implement the same interface.

• Shorten: Model.QueryStorage

  If a namespace contains only a small number of types, maybe you don't need that namespace at all.

• Make enterprisey: Model.ProjectSystem.Project

  This can work especially for features that are important part of your product, so they deserve their own name.

Two of them are interfaces so I could consider prefixing them with I but I really don't like this convention.

You really should, if your code is used by others (i.e. it's a library) or if you don't want to confuse newcomers to your code.