MYSQL Sub Query COUNT WHERE

Question

I am trying to create an SQL query that varies based on options sent in from a form. Within this I want to try and share the effects of the main WHERE clause statement with the WHERE clause on a sub query.

Taking pass_count for example, I want to count the number of rows where total_passfail = "Pass". This number may however change due the implication of the main queries WHERE function (within the main WHERE function I have 8 possible options such as date span, user, team, department which shape the overall data accordingly).

Is there any way to make the overall WHERE clause affect the sub query rather than me having to add 8 more WHERE's to each sub query. Effectively I just want the sub-query WHERE clause to act on top of the dataset the main query returns.

Any help would be much appreciated.

$query = $this->db->join('users', 'users.staff_id = quality.staff_id')
->join('user_info', 'user_info.staff_id = users.staff_id')
->join('teams', 'teams.team_id = users.team_id')
->join('departments', 'teams.dept_id = departments.dept_id')
->join('quality_results', 'quality_results.qms_id = quality.qms_id')
->where('quality.published !=', "")
->where('quality.published !=', "0000-00-00 00:00:00")
->select('users.staff_id, user_info.name, user_info.surname, teams.team_name, departments.dept_name, COUNT(quality.qms_id) AS num_assessments, (SELECT (SUM(quality_results.total_result) / COUNT(quality_results.total_result))) AS average_result, (SELECT COUNT(quality_results.total_passfail) FROM quality_results WHERE quality_results.total_passfail = "Pass") AS pass_count');  

if (strlen($query_array['task_date_from'])) { 
$query->where('quality.task_datetime >=', $query_array['task_date_from']); 
}
if (strlen($query_array['task_date_to'])) { 
$query->where('quality.task_datetime <=', $query_array['task_date_to']); 
}
     (+ 4 MORE IF STATEMENTS HERE)

$result = $query->get('quality');

I've also tired replacing the subquery with the following but get an error instead:

SUM(IF(quality_results.total_passfail = "Pass", 1,0)) AS pass_count

Here's my raw SQL code:

SELECT `users`.`staff_id`, `user_info`.`name`, `user_info`.`surname`, `teams`.`team_name`, `departments`.`dept_name`, COUNT(quality.qms_id) AS num_assessments, (SELECT (AVG(quality_results.total_result))) AS average_result, (SELECT COUNT(quality_results.total_passfail) FROM quality_results WHERE quality_results.total_passfail = "Pass") AS pass_count FROM (`quality`) JOIN `users` ON `users`.`staff_id` = `quality`.`staff_id` JOIN `user_info` ON `user_info`.`staff_id` = `users`.`staff_id` JOIN `teams` ON `teams`.`team_id` = `users`.`team_id` JOIN `departments` ON `teams`.`dept_id` = `departments`.`dept_id` JOIN `quality_results` ON `quality_results`.`qms_id` = `quality`.`qms_id` JOIN `quality_tasks` ON `quality`.`task_id` = `quality_tasks`.`task_id` WHERE `quality`.`published` != '' AND `quality`.`published` != '0000-00-00 00:00:00' AND `quality`.`task_datetime` >= '2011-04-09' AND `quality`.`task_datetime` <= '2011-05-09' AND `teams`.`dept_id` = '1'

Answer 1

Formatted SQL:

SELECT `users`.`staff_id`, `user_info`.`name`, `user_info`.`surname`,
       `teams`.`team_name`, `departments`.`dept_name`,
       COUNT(quality.qms_id) AS num_assessments,
      (SELECT (AVG(quality_results.total_result))) AS average_result,
      (SELECT COUNT(quality_results.total_passfail)
         FROM quality_results
         WHERE quality_results.total_passfail = "Pass") AS pass_count
FROM (`quality`)
JOIN `users` ON `users`.`staff_id` = `quality`.`staff_id`
JOIN `user_info` ON `user_info`.`staff_id` = `users`.`staff_id`
JOIN `teams` ON `teams`.`team_id` = `users`.`team_id`
JOIN `departments` ON `teams`.`dept_id` = `departments`.`dept_id`
JOIN `quality_results` ON `quality_results`.`qms_id` = `quality`.`qms_id`
JOIN `quality_tasks` ON `quality`.`task_id` = `quality_tasks`.`task_id`
WHERE `quality`.`published` != ''
  AND `quality`.`published` != '0000-00-00 00:00:00'
  AND `quality`.`task_datetime` >= '2011-04-09'
  AND `quality`.`task_datetime` <= '2011-05-09'
  AND `teams`.`dept_id` = '1'

Currently your pass_count not takes into account main where, as it`s subquery. But you could add for each column like pass_count left joined quality_results, as here:

SELECT
    `users`.`staff_id`, `user_info`.`name`, `user_info`.`surname`, `teams`.`team_name`, `departments`.`dept_name`,
    COUNT(quality.qms_id) AS num_assessments,
    (SELECT (AVG(quality_results.total_result))) AS average_result, -- It`s a total average result -- as a whole on all system
    count(quality_results_passed.total_passfail) AS pass_count -- And this will be quality_results, that will take into account your main where
FROM (`quality`)
JOIN `users` ON `users`.`staff_id` = `quality`.`staff_id`
JOIN `user_info` ON `user_info`.`staff_id` = `users`.`staff_id`
JOIN `teams` ON `teams`.`team_id` = `users`.`team_id`
JOIN `departments` ON `teams`.`dept_id` = `departments`.`dept_id`
JOIN `quality_results` ON `quality_results`.`qms_id` = `quality`.`qms_id`
LEFT JOIN `quality_results` as `quality_results_passed`
    ON `quality_results_passed`.`qms_id` = `quality`.`qms_id`
    and quality_results.total_passfail = "Pass"
JOIN `quality_tasks` ON `quality`.`task_id` = `quality_tasks`.`task_id`
WHERE `quality`.`published` != '' AND `quality`.`published` != '0000-00-00 00:00:00'
AND `quality`.`task_datetime` >= '2011-04-09' AND `quality`.`task_datetime` <= '2011-05-09' AND `teams`.`dept_id` = '1'