如何從CURDATE（）前n天從MySQL獲得值（）

Question

我想要連接4個表以列出表中所有具有從上次更新到當前日期的持續時間的值，而不是其他表中的持續時間，表中給出如下（我的英語不是很好理解這樣正與examble解釋）

第一臺daily_tasks

+---------+---------+ 
| task_id | type_id | 
+---------+---------+ 
|  1 |  1 | 
|  2 |  1 | 
|  3 |  2 | 
+---------+---------+ 

二表daily_task_report

+-----------+---------+------------+ 
| report_id | task_id | task_date | 
+-----------+---------+------------+ 
|   1 |  1 | 2015-09-10 | 
|   2 |  3 | 2015-09-10 | 
|   3 |  1 | 2015-09-11 | 
|   4 |  3 | 2015-09-16 | 
+-----------+---------+------------+ 

三表duration_types

+---------+---------------+------------------------+ 
| type_id | duration_type | duration_time(in days) | 
+---------+---------------+------------------------+ 
|  1 | Daily Task |      1 | 
|  2 | Weekly Task |      6 | 
|  3 | Monthly Task |      26 | 
|  4 | Yearly Task |     313 | 
+---------+---------------+------------------------+ 

四表calendar

+--------+------------+---------+ 
| cal_id | cal_date | holiday | 
+--------+------------+---------+ 
|  1 | 2015-09-10 |  0 | 
|  2 | 2015-09-11 |  0 | 
|  3 | 2015-09-12 |  0 | 
|  4 | 2015-09-13 |  1 | 
+--------+------------+---------+ 

這裏daily_tasks.type_id是duration_types.type_id和daily_task_report.task_id爲daily_tasks.task_id。我想選擇所有task_id那些task_date和current_date之間的差異將大於duration_time，同時計算我必須避免從有holiday=1的日期的持續時間。 我試過查詢，但不正確，我得到的值不包括calendar表，但這不是一個好方法，查詢需要更多時間來執行。

"SELECT dailyTasks.task_id FROM 
          (SELECT tab.* FROM (SELECT 
          tasks.task_type,report.* 
          FROM daily_tasks AS tasks 
          LEFT JOIN daily_task_reports AS report ON tasks.task_id=report.task_id 
          WHERE 1 ORDER BY report.task_date DESC) as tab GROUP BY tab.d_task_id) AS dailyTasks 
          LEFT JOIN duration_types AS type ON dailyTasks.task_type=type.type_id 
          WHERE DATEDIFF(CURDATE(),dailyTasks.task_date)>=type.duration_time" 

請人幫忙，我堅持在本節

Answer 1

根據給定的表您的查詢

一些意想不到的文字或未知列嘗試此查詢

"SELECT dailyTasks.d_task_id FROM 
         (SELECT tab.* FROM 
           (SELECT tasks.type_id,report.* FROM daily_tasks AS tasks 

            LEFT JOIN daily_task_reports AS report ON tasks.task_id=report.task_id 

            ORDER BY report.task_date DESC) 

           as tab GROUP BY tab.task_id) AS dailyTasks 

           LEFT JOIN duration_types AS type ON dailyTasks.type_id=type.type_id 

         WHERE DATEDIFF(CURDATE(),dailyTasks.task_date)>=type.duration_time" 

它可以是一個LSO工作在單一的查詢

SELECT tasks.task_id FROM daily_tasks AS tasks 

     LEFT JOIN daily_task_reports AS report ON tasks.task_id=report.task_id 
     LEFT JOIN duration_types AS type ON tasks.type_id = type.type_id and DATEDIFF(CURDATE(),report.task_date) >= type.duration_time 

*我試過，但不排除id，這將有假期日曆 您可以在編碼端創建我給你包含新的查詢與日曆 *

SELECT tasks.task_id,report.task_date,calendar.holiday FROM daily_tasks AS tasks 

     LEFT JOIN daily_task_reports AS report ON tasks.task_id=report.task_id 
     LEFT JOIN duration_types AS type ON tasks.type_id = type.type_id and DATEDIFF(CURDATE(),report.task_date) >= type.duration_time 
     LEFT JOIN calendar ON report.task_date=calendar.cal_date 
     where calendar.holiday = '0' 
     order By report.task_date desc