public function addField($field)
	{
		if (is_string($field))
		{
			if ($field === 'id')
			{
				$this->addField([
					'id' => [
						'type'           => 'INT',
						'constraint'     => 9,
						'auto_increment' => true,
					],
				]);
				$this->addKey('id', true);
			}
			else
			{
				if (strpos($field, ' ') === false)
				{
					throw new \InvalidArgumentException('Field information is required for that operation.');
				}

				$this->fields[] = $field;
			}
		}

		if (is_array($field))
		{
			$this->fields = array_merge($this->fields, $field);
		}

		return $this;
	}