为什么我的存储过程不会返回预期的结果？

Question

嗨，我有以下存储过程......

DELIMITER $$ 

DROP PROCEDURE IF EXISTS `CouponCrusaderDev`.`sp_tblemailcampaignLoadTop4`$$ 

CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_tblemailcampaignLoadTop4`(p_UserID Int(11)) 
    SQL SECURITY INVOKER 
BEGIN 
SELECT EC.*,(Select MailChimpCampaignID from tblcampaignschedule where EC.CampaignID=tblcampaignschedule.CampaignID AND tblcampaignschedule.MailChimpCampaignID IS NOT NULL) as MailChimpCampaignID, 
(Select count(MailChimpCampaignID) from tblcampaignschedule) as msent,CT.CampaignType, 
(Select tblcampaignschedule.ScheduleDateTime from tblcampaignschedule 
where EC.CampaignID=tblcampaignschedule.CampaignID order By ScheduleDateTime desc limit 1) as CampaignDateTime, 
(Select Count(*) from tblemailsent ES 
inner join tblcampaignschedule CS on CS.CampaignSceduleID= ES.CampaignSceduleID 
where ES.Status= 'ProcessedMessage' and CS.CampaignID = EC.CampaignID)as Sent 
FROM tblemailcampaign EC 
inner join tblcampalgntype CT on CT.CampaignTypeID= EC.CampaignTypeID 
inner join tblcompanies C On EC.CompanyID = C.CompanyID 
WHERE (p_UserID = 0 OR C.AddUserID = p_UserID) 
order by CampaignDateTime desc limit 4 
; 
END$$ 

DELIMITER ; 

，我要展现MailChinpCampaignID不是空，因此因此，我做了下面的代码........

SELECT EC.*,(Select MailChimpCampaignID from tblcampaignschedule where EC.CampaignID=tblcampaignschedule.CampaignID AND tblcampaignschedule.MailChimpCampaignID IS NOT NULL) as MailChimpCampaignID, 

但它返回的所有空mailchimpcampaignid的我能做些什么

Answer 1

您的查询返回null，因为在“tblcampaignschedule”没有行与匹配的ID和非空MailChimpCampaignID。我认为最好的做法是内部连接到'tblcampaignschedule'，并过滤出这些空值的方式..

这是我该怎么做（做了一些其他更改也摆脱（我认为）不必要的子-selects）。但是，除非您向我们展示您的表格结构以及一些示例数据，否则这至少是一种猜测。

DELIMITER $$ 

DROP PROCEDURE IF EXISTS `CouponCrusaderDev`.`sp_tblemailcampaignLoadTop4`$$ 

CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_tblemailcampaignLoadTop4`(p_UserID Int(11)) 
    SQL SECURITY INVOKER 
BEGIN 
SELECT EC.*, 
Select tcs.MailChimpCampaignID as MailChimpCampaignID, 
count(distinct tcs.MailChimpCampaignID)as msent, 
CT.CampaignType, 
max(tcs.ScheduleDateTime) as CampaignDateTime, 
Count(*) as Sent 
FROM tblemailcampaign EC 
inner join tblcampalgntype CT on CT.CampaignTypeID= EC.CampaignTypeID 
inner join tblcompanies C On EC.CompanyID = C.CompanyID 
inner join tblcampaignschedule tcs ON EC.CampaignID=tcs.CampaignID AND MailChimpCampaignID IS NOT NULL 
inner join tblemailsent ES ON tcs.CampaignSceduleID= ES.CampaignSceduleID AND ES.Status= 'ProcessedMessage' 
WHERE (p_UserID = 0 OR C.AddUserID = p_UserID) 
order by CampaignDateTime desc limit 4 
; 
END$$ 

DELIMITER ; 

编辑：

DELIMITER $$ 

DROP PROCEDURE IF EXISTS `CouponCrusaderDev`.`sp_tblemailcampaignLoadTop4`$$ 

CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_tblemailcampaignLoadTop4`(p_UserID Int(11)) 
    SQL SECURITY INVOKER 
BEGIN 
SELECT EC.*, 
Select tcs.MailChimpCampaignID as MailChimpCampaignID, 
(Select count(MailChimpCampaignID) from tblcampaignschedule) as msent,CT.CampaignType, 
(Select tblcampaignschedule.ScheduleDateTime from tblcampaignschedule 
where EC.CampaignID=tblcampaignschedule.CampaignID order By ScheduleDateTime desc limit 1) as CampaignDateTime, 
(Select Count(*) from tblemailsent ES 
inner join tblcampaignschedule CS on CS.CampaignSceduleID= ES.CampaignSceduleID 
where ES.Status= 'ProcessedMessage' and CS.CampaignID = EC.CampaignID)as Sent 
FROM tblemailcampaign EC 
inner join tblcampalgntype CT on CT.CampaignTypeID= EC.CampaignTypeID 
inner join tblcompanies C On EC.CompanyID = C.CompanyID 
inner join tblcampaignschedule tcs ON EC.CampaignID=tcs.CampaignID AND MailChimpCampaignID IS NOT NULL 
WHERE (p_UserID = 0 OR C.AddUserID = p_UserID) 
order by CampaignDateTime desc limit 4 
; 
END$$ 

DELIMITER ;