Here's the commands we'll be using to create the output below:

Small

$this->Where('id', 5)->End();

Medium

$this->Where('status', array(1,5,2))->Also('timestamp', '1/1/2000', '<')->End();

Large

$this->Where('modified', 'added', '<', DBWhere::VALUE_IS_COLUMN)
    ->Also('added', 'dateAdd(d, -10, getDate())', '>', DBWhere::VALUE_IS_SPECIAL)
    ->Also('category_id', 2)
    ->Also(
        $this->Where('status', array(1,2))
        ->Either('is_admin', true)
        ->Either('name', "O'Rielly")
    )->End();

DBWhere
Small: WHERE id = 5
Medium: WHERE status IN (1, 5, 2) AND timestamp < 1/1/2000

 Large: WHERE modified < added AND added > dateAdd(d, -10, getDate()) AND category_id = 2 AND (WHERE status IN (1, 2) OR is_admin = 1 OR name = O'Rielly)

MySqlWhere
Small: WHERE `id` = '5'
Medium: WHERE `status` IN ('1', '5', '2') AND `timestamp` < '1/1/2000'

 Large: WHERE `modified` < `added` AND `added` > dateAdd(d, -10, getDate()) AND `category_id` = '2' AND (WHERE `status` IN ('1', '2') OR `is_admin` = '1' OR `name` = 'O\'Rielly')

TSqlWhere
Small: WHERE [id] = '5'
Medium: WHERE [status] IN ('1', '5', '2') AND [timestamp] < '1/1/2000'

 Large: WHERE [modified] < [added] AND [added] > dateAdd(d, -10, getDate()) AND [category_id] = '2' AND (WHERE [status] IN ('1', '2') OR [is_admin] = '1' OR [name] = 'O''Rielly')