DROP TABLE IF EXISTS `org_apiinteg_assets`;
DROP TABLE IF EXISTS `assessmentinstances`;

CREATE TABLE `org_apiinteg_assets` (
  `id` varchar(20) NOT NULL default '0',
  `instance_id` varchar(20) default NULL,
  PRIMARY KEY  (`id`)
) ENGINE= MyISAM DEFAULT CHARSET=utf8 PACK_KEYS=1;

CREATE TABLE `assessmentinstances` (
  `id` varchar(20) NOT NULL default '0',
  `title` varchar(180) default NULL,
  PRIMARY KEY  (`id`)
) ENGINE= MyISAM DEFAULT CHARSET=utf8 PACK_KEYS=1;


insert into assessmentinstances(id, title) values ('14026lvplotw6','One radio question survey');
insert into org_apiinteg_assets(id, instance_id) values ('8kp9wgx43jflrgjfe','14026lvplotw6');

assessmentinstances
+---------------+---------------------------+
|        id     |          title            |
+---------------+---------------------------+
| 14026lvplotw6 | One radio question survey |
+---------------+---------------------------+

org_apiinteg_assets
+-------------------+---------------+
|        id         |  instance_id  |
+-------------------+---------------+
| 8kp9wgx43jflrgjfe | 14026lvplotw6 |
+-------------------+---------------+

SELECT ai.id, COUNT(*) AS `count`
FROM assessmentinstances ai INNER JOIN org_apiinteg_assets a
    ON a.instance_id = ai.id
WHERE ai.id = '14026lvplotw6'
AND a.id != '8kp9wgx43jflrgjfe';

null, 0

'14026lvplotw6','0'