我正在尝试创建一个 SQL 查询，该查询根据从表单发送的选项而变化。在此，我想尝试分享主 WHERE 子句语句与 WHERE 子句对子查询的影响。

以pass_count为例，我想统计total_passfail = "Pass"的行数。然而，由于主要查询 WHERE 函数的含义，这个数字可能会发生变化(在主要 WHERE 函数中，我有 8 个可能的选项，例如日期跨度、用户、团队、部门，它们相应地塑造了整体数据)。

有什么方法可以使整个 WHERE 子句影响子查询，而不是我必须向每个子查询再添加 8 个 WHERE。实际上，我只希望子查询 WHERE 子句作用于主查询返回的数据集之上。

如有任何帮助，我们将不胜感激。

$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');

我也厌倦了用以下内容替换子查询，但得到了一个错误:

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

这是我的原始 SQL 代码:

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'

最佳答案

Formatted数据库:

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'

目前你的 pass_count 没有考虑到 main where，因为它是子查询。但是您可以为每一列添加 pass_count left joined quality_results，如下所示:

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'

关于MYSQL 子查询 COUNT WHERE，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/5904634/