INSERT INTO `#__extensions` (`name`, `type`, `element`, `folder`, `client_id`, `enabled`, `access`, `protected`, `locked`, `manifest_cache`, `params`, `custom_data`, `ordering`, `state`)
SELECT 'plg_captcha_powcaptcha', 'plugin', 'powcaptcha', 'captcha', 0, 1, 1, 0, 1, '', '{}', '', 0, 0
WHERE NOT EXISTS (SELECT * FROM `#__extensions` e WHERE e.`type` = 'plugin' AND e.`element` = 'powcaptcha' AND e.`folder` = 'captcha' AND e.`client_id` = 0);