Question

我几天来一直试图修复我的查询。它应该按月分组，如果没有找到记录则返回0。这是我的疑问：

SELECT 
school_id,
IF(school="Utah Valley University","Schoo1",
IF(school="Weber State University","School2", school)) school,  
online,
pif_price,
COUNT(pif_price),
pif_price,
payment_plans.id AS Payment,
COUNT(IFNULL(x1.Month,0))

FROM users

INNER JOIN students 
    ON users.id = students.user_id
INNER JOIN students_terms
    ON students.id = students_terms.student_id  
INNER JOIN terms
    ON students_terms.term_id = terms.id
INNER JOIN courses      
    ON terms.course_id = courses.id 
INNER JOIN schools      
    ON courses.school_id = schools.id
INNER JOIN payment_plans
    ON students_terms.payment_plan_id = payment_plans.id    
INNER JOIN (SELECT 
            DISTINCT MONTH(enroll_date) AS Month,
            enroll_date
            FROM students_terms
            GROUP BY Month ASC) AS x1
    ON students_terms.enroll_date = x1.enroll_date
WHERE
NOT pif_price = 229
AND NOT pif_price = 429
AND NOT pif_price = 1199        
AND students_terms.enroll_date >="2017-01-01"
AND students_terms.enroll_date < CURDATE()

GROUP BY
month

如您所见，我试图从嵌套表中获取数字1-12。

即使这样，查询也会运行，但不会带来任何数据。

我可以通过取出嵌套表来重新获取数据，如下所示：

SELECT 
school_id,
IF(school="Utah Valley University","School1",
IF(school="Weber State University","School2", school)) school,  
online,
pif_price,
COUNT(pif_price),
payment_plans.id AS Payment,
CONCAT(MONTH(students_terms.enroll_date), "/",     YEAR(students_terms.enroll_date)) AS Enroll_Date

FROM users

INNER JOIN students 
    ON users.id = students.user_id
INNER JOIN students_terms
    ON students.id = students_terms.student_id  
INNER JOIN terms
    ON students_terms.term_id = terms.id
INNER JOIN courses      
    ON terms.course_id = courses.id 
INNER JOIN schools      
    ON courses.school_id = schools.id
INNER JOIN payment_plans
    ON students_terms.payment_plan_id = payment_plans.id    

WHERE
NOT pif_price = 229
AND NOT pif_price = 429
AND NOT pif_price = 1199        
AND enroll_date >="2017-01-01"
AND enroll_date < CURDATE()

GROUP BY 
YEAR(enroll_date),
MONTH(enroll_date),
pif_price

在这里研究我能够发现，如果制作一个“月表”并加入它，那将解决我的问题。问题是，我没有权限向DB添加表。这就是为什么我试图让它与嵌套的“月表”一起工作。

有没有办法让这段代码无需添加“月份表？”

感谢您的帮助！

MySql按月计算以显示没有数据的月份

0 个答案: