SQL WHERE语句不能与RIGHT JOIN一起使用

Question

我有以下SQL查询，但问题是WHERE语句无法正常使用RIGHT JOIN：

   SELECT COUNT(*) no_of_application_by_status, applicationStatusName
    FROM `Application` `a`
    right JOIN `ApplicationStatus` `ass` ON `ass`.`applicationStatusId`=`a`.`applicationStatusId`
    WHERE `applicationTypeId` = '40007' 
    GROUP BY `ass`.`applicationStatusId`

我想让applicationStatusName no_of_application_by_status = 0

Answer 1

您必须将where条件放入on子句：

SELECT COUNT(*) no_of_application_by_status, applicationStatusName
    FROM `Application` `a`
    right JOIN `ApplicationStatus` `ass` ON `ass`.`applicationStatusId`=`a`.`applicationStatusId`
   and `applicationTypeId` = '40007' 
    GROUP BY `ass`.`applicationStatusId`

如果不这样做，联接结果将被where条件过滤。

Answer 2

使用Having想要获取群组计数= 0或者如果您只想计算no_of_application_by_status = 0的记录，然后在AND <中使用WHERE条件/ p>

For Group Count = 0

SELECT COUNT(*) no_of_application_by_status, 
    applicationStatusName
FROM Application a
RIGHT JOIN ApplicationStatus ass ON ass.applicationStatusId=a.applicationStatusId
WHERE applicationTypeId = '40007'
HAVING COUNT(*) = 0
GROUP BY ass.applicationStatusId

no_of_application_by_status = 0

的OR计数

SELECT COUNT(*) no_of_application_by_status, 
    applicationStatusName
FROM Application a
RIGHT JOIN ApplicationStatus ass ON ass.applicationStatusId=a.applicationStatusId
WHERE applicationTypeId = '40007' AND no_of_application_by_status = 0
GROUP BY ass.applicationStatusId