Mysql group_concat with distinct and where 给出奇怪的结果

Question

我有以下查询可以正常工作（见下文）。

但是当我添加一个条件时，例如AND (specialtyName = '...') 主要结果很好，但是 GROUP_CONCAT 只显示匹配条件的结果。

谁能帮我解决这个问题？

提前致谢。

弗雷德。

SELECT 

    tblJobs.jobID, 
    tblJobs.jobName, 
    DATE_FORMAT(tblJobs.jobDate,'%d-%m-%Y'), 

    tblCompanies.companyID, 
    tblCompanies.companyName, 
    tblCompanies.companyNameConvert, 

    GROUP_CONCAT(DISTINCT tblSpecialties.specialtyName 
        ORDER BY FIELD (
            specialtyName, 
            'specialtyName1', 
            'specialtyName2', 
            'specialtyName3'), 
            specialtyName ASC) 
        AS specialtyNames, 

    GROUP_CONCAT(DISTINCT tblSpecialties.specialtyNameConvert 
        ORDER BY FIELD (
            specialtyName, 
            'specialtyName1', 
            'specialtyName2', 
            'specialtyName3'), 
            specialtyName ASC) 
        AS specialtyNamesConvert, 

    GROUP_CONCAT(DISTINCT tblRegions.regionName), 
    GROUP_CONCAT(DISTINCT tblRegions.regionNameConvert) 

FROM tblJobs 

LEFT JOIN tblCompanies ON 
(tblJobs.jobCompany = tblCompanies.companyID) 

LEFT JOIN tblSpecialties ON 
FIND_IN_SET(tblSpecialties.specialtyID, REPLACE(tblJobs.jobSpecialty,' ',',')) 

LEFT JOIN tblRegions ON 
FIND_IN_SET(tblRegions.regionID, REPLACE(tblJobs.jobRegion,' ',','))

WHERE 

    AND jobActive = '1' 
    AND jobDate >= '2013-01-01' 
    AND companyActive = '1' 

GROUP BY jobID 
ORDER BY jobDate DESC, jobID DESC, jobCompany DESC

Answer 1

如果你说：

WHERE jobActive = '1' AND jobDate >= '2013-01-01' AND companyActive = '1' AND
      specialties = XXX

那么你只会得到这些专业。过滤是在聚合之前完成的。注意：在where 子句中包含这样的条件也会将外部连接变为内部连接。您的联接可能在正确对齐的外键关系上，因此内部联接可能是合适的。

我猜你真正想要的是按具有该专业的人过滤工作，但保留所有其他信息。您想在聚合之后进行过滤。使用having 子句而不是where 子句来做到这一点：

having sum(specialties = XXX) > 0;

这将只保留具有特定专业的行，并保留所有其他信息。

Answer 2

我想为您的表和子查询使用别名可以解决您的问题。 你可以试试这样：

SELECT 

tblJobs.jobID, 
tblJobs.jobName, 
DATE_FORMAT(tblJobs.jobDate,'%d-%m-%Y'), 

tblCompanies.companyID, 
tblCompanies.companyName, 
tblCompanies.companyNameConvert,  
(SELECT GROUP_CONCAT(DISTINCT ts.specialtyName 
        ORDER BY FIELD (
            specialtyName, 
            'specialtyName1', 
            'specialtyName2', 
            'specialtyName3'), 
            specialtyName ASC) 
        FROM tblSpecialties ts) AS specialtyNames , 
, ... ,
FROM tblJobs 

LEFT JOIN tblCompanies ON 
(tblJobs.jobCompany = tblCompanies.companyID) 

LEFT JOIN tblSpecialties ON 
FIND_IN_SET(tblSpecialties.specialtyID, REPLACE(tblJobs.jobSpecialty,' ',',')) 

LEFT JOIN tblRegions ON 
FIND_IN_SET(tblRegions.regionID, REPLACE(tblJobs.jobRegion,' ',','))

WHERE 

    AND jobActive = '1' 
    AND jobDate >= '2013-01-01' 
    AND companyActive = '1' 

GROUP BY jobID 
ORDER BY jobDate DESC, jobID DESC, jobCompany DESC

我没有测试此代码，但它可以提供帮助。