MySQL 交叉表查询中缺少列答案

【问题标题】：Missing Column(s) in MySQL Crosstab QueryMySQL 交叉表查询中缺少列
【发布时间】：2020-03-18 00:50:36
【问题描述】：

因此，我有一个非常复杂的交叉表查询供我的客户管理，他负责管理各个大学的学生资助。查询是动态的，因此它在存储过程中构建为一个长字符串，然后准备、执行和释放。

我已经能够提取最终的查询，大约 2000 个字符长。

select concat(s.LastName, ', ', s.FirstName, ' ', ifnull(s.MiddleInit, '')) as StudentName, p.SSN, 
case @fullSSN when 0 then concat('xxxx-xx-', right(p.ssn, 4)) else concat(left(p.ssn, 3), '-', 
substr(p.ssn, 4, 2), '-', right(p.ssn, 4)) end as formattedSSN, 
sp.AwardYear, c.CampusName, es.EnrollmentStatus, sp.LoanPeriodFrom, sp.LoanPeriodTo, pg.ProgramName, 
concat(s.Address1, ', ', s.City, ', ', s.State, ' ', s.Zip) as Address, s.Email, s.DOB, 
sp.StartDate, sp.EndDate as LDA, sp.VerifyType,  

sum(case when FedPgmName = 'DL Subsidized' then Amount end) as 'DL Subsidized', 
sum(case when FedPgmName = 'DL Unsubsidized' then Amount end) as 'DL Unsubsidized', 
sum(case when FedPgmName = 'Pell' then Amount end) as 'Pell', 
sum(case when FedPgmName = 'DL PLUS' then Amount end) as 'DL PLUS', 
sum(case when FedPgmName = 'FSEOG' then Amount end) as 'FSEOG', 
sum(case when FedPgmName = 'FWS' then Amount end) as 'FWS' 

from Payments as p inner join Student as s on p.SchoolID = s.SchoolID and p.SSN = s.SSN inner join                     
(select SchoolID, SSN, Max(StudentProfileID) as MaxProfileID from StudentProfile group by SchoolID,     
SSN) as max on p.SchoolID = max.SchoolID and p.ssn = max.ssn inner join StudentProfile as sp on 
max.SchoolID = sp.SchoolID and max.SSN = sp.SSN and max.MaxProfileID = sp.StudentProfileID inner 
join Program as pg on sp.SchoolID = pg.SchoolID and sp.ProgramID = pg.ProgramID inner join     as fp 
on p.FedPgmID = fp.FedPgmID inner join Campuses as c on sp.SchoolID = c.SchoolID and sp.CampusID = 
c.CampusID inner join EnrollmentStatus as es on sp.EnrollmentStatusID = es.EnrollmentStatusID where 
p.SchoolID = 'cbd' and CkDate between '2018-01-01' and '2018-12-31' and sp.ProgramID in(161, 24, 25, 
168, 165, 166, 14, 159, 160, 13, 150, 151, 17, 23, 10, 15, 2, 16, 3, 26, 9, 21, 22, 1, 11, 12, 19, 
20, 4, 18, 8, 5, 6, 7) and p.FedPgmID in(1, 8, 9, 10, 5, 6, 23) and sp.EnrollmentStatusID in(1, 10, 
2, 3, 4, 5, 6, 7, 8, 9) and ifnull(CkNo, 0) > 0 group by StudentName, SSN, formattedSSN, AwardYear, 
CampusName, EnrollmentStatus, LoanPeriodFrom, LoanPeriodTo, ProgramName

确切地知道这里发生了什么并不重要，除了我的问题涉及上面的交叉表代码，其中有几种不同联邦程序名称的情况。如果基础数据包含提到的所有不同程序，那么一切正常。如果数据中缺少任何提到的情况（例如没有带有“FWS”的行），那么该列不会显示在结果中，并且我的代码有问题，因为它期望返回所有列。

所以我想弄清楚如何确保返回所有列。如果我在生成的 SQL 代码的开头添加以下内容，则可以正常工作：

select '' as StudentName, '' as SSN, '' as formattedSSN, '' as AwardYear, '' as CampusName, '' as EnrollmentStatus, 
'' as LoanPeriodFrom, 
'' as LoanPeriodTo, '' as ProgramName, '' as Address, '' as Email, '' as DOB, '' as StartDate, '' as LDA, '' as VerifyType, 
select 0 as 'DL Subsidized', 0 as 'DL Unsubsidized', 0 as 'Pell', 0 as 'DL PLUS', 0 as 'FSEOG', 0 as 'FWS'
union

使用上述代码使查询成为联合查询有效。返回所有列，但我在顶部有一个“空”行，我必须为其编码。

请记住，查询非常复杂，并且必须使用大量连接来构建，而且我必须执行 group_concat 来获取可能的联邦程序的名称。这为我创建了 case 语句，这些语句被注入到主 SQL 语句中。

除了执行联合查询之外，还有什么方法可以强制显示所有列？希望我把问题说清楚了。

谢谢...

编辑：事实证明，添加联合查询毕竟不起作用。我正在耗尽已经包含所有联邦计划记录的数据。如果我使用不包含某些联邦程序的数据集运行该联合查询，则会收到关于 2 个查询与列数不匹配的错误。所以我仍然有返回交叉表部分中所有可能的列的问题。

【问题讨论】：

标签： mysql crosstab dynamicquery

【解决方案1】：

无法解决这个问题，所以我以不同的方式解决了这个问题。由于交叉表查询不会在交叉表中提供任何在基础数据中不是有效值的列，因此我创建了一个包含所有可能列的表，然后从交叉表查询中截断并填充该表。最后，从该表中选择。现在会显示所有可能的列。

【讨论】：