Mysql 显示之间的所有日期，即使分组依据中没有结果

展示这个

预期结果

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您可以创建一个日期列表，用于在表中列出和加入日期。下面查询的表c是日期表

SELECT Count(Phq_2) as Phq_2, Date(created) as created
FROM `survey` 
WHERE Phq_2 != '' 
GROUP BY Date(created) 
ORDER BY Date(created) ASC

结果

SELECT c.date, 
       COUNT(s.phq_2) 
  FROM (select adddate('1970-01-01',t4.i*10000 + t3.i*1000 + t2.i*100 + t1.i*10 + t0.i) date from
        (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t0,
        (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t1,
        (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t2,
        (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t3,
        (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t4
       ) c
  LEFT JOIN `survey` s 
    ON c.date = s.created
 WHERE s.phq_2 != '' 
   AND c.date BETWEEN '2017-08-30' AND '2017-09-06'
 GROUP BY c.date
 ORDER BY c.date

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如果希望将c.date的日期固定在“2017-08-30”和“2017-09-06”之间，则可以在子查询中使用从表中创建的列的结果MIN（）和MAX（）。您可以创建一个日期列表，用于在表中列出和加入。下面查询的表c是日期表

SELECT Count(Phq_2) as Phq_2, Date(created) as created
FROM `survey` 
WHERE Phq_2 != '' 
GROUP BY Date(created) 
ORDER BY Date(created) ASC

结果

SELECT c.date, 
       COUNT(s.phq_2) 
  FROM (select adddate('1970-01-01',t4.i*10000 + t3.i*1000 + t2.i*100 + t1.i*10 + t0.i) date from
        (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t0,
        (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t1,
        (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t2,
        (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t3,
        (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t4
       ) c
  LEFT JOIN `survey` s 
    ON c.date = s.created
 WHERE s.phq_2 != '' 
   AND c.date BETWEEN '2017-08-30' AND '2017-09-06'
 GROUP BY c.date
 ORDER BY c.date

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如果您希望将c.date的日期固定在“2017-08-30”和“2017-09-06”之间，您可以在子查询中使用从表中创建的列的结果MIN（）和MAX（），您需要创建一个临时表[WITH]，该表生成您感兴趣的所有日期，并将左侧连接到查询中。我认为这是一个复杂的问题，我已经见过很多次了！请帮助我，我试图从现有问题中解决一些想法，但考虑到处理应用程序代码中的数据显示问题，您需要创建一个临时表[WITH]，生成您感兴趣的所有日期以及查询的左连接。我认为这是一个复杂的问题，我已经见过很多次了！在Please help me中的一些想法我试图从现有问题中解决，但在vainConsider中处理应用程序CodeTool中的数据显示问题，所以只需使用此方法并将左连接添加到我们的表中，修复我的问题，谢谢。酷，所以只需使用此方法并将左连接添加到我们的表中，修复我的问题，谢谢。