右外mysql中

Question

加入的問題我寫了一個查詢，以便從四個不同的表中獲取數據如下：

SELECT crm_countries.country_name as Country,crm_support_inquiry.event_name as Event, crm_inquiry_perticipant.company as Company,crm_inquiry_perticipant.contact_name ContactPerson,crm_inquiry_perticipant.email, 

GROUP_CONCAT(CONVERT(Expogroup, CHAR(200)) SEPARATOR '/') AS Expogroup,GROUP_CONCAT(CONVERT(Abdas, CHAR(200)) SEPARATOR '/') AS Abdas, GROUP_CONCAT(CONVERT(AfricaDetails, CHAR(200)) SEPARATOR '/') AS AfricaDetails, GROUP_CONCAT(CONVERT(Kenyadetails, CHAR(200)) SEPARATOR '/') AS Kenyadetails,GROUP_CONCAT(CONVERT(Findexporters, CHAR(200)) SEPARATOR '/') AS Findexporters,GROUP_CONCAT(CONVERT(Dubaiexporters, CHAR(200)) SEPARATOR '/') AS Dubaiexporters,GROUP_CONCAT(CONVERT(IndiaExportNews, CHAR(200)) SEPARATOR '/') AS IndiaExportNews FROM (SELECT inquiry_id,event_id,event_name,CASE WHEN mailer_id = 1 THEN CONCAT(Edition,' - ',sent_on) END AS Expogroup,CASE WHEN mailer_id = 2 THEN CONCAT(Edition,' - ',sent_on) END AS Abdas,CASE WHEN mailer_id = 3 THEN CONCAT(Edition,' - ',sent_on) END AS AfricaDetails,CASE WHEN mailer_id = 4 THEN CONCAT(Edition,' - ',sent_on) END AS Kenyadetails,CASE WHEN mailer_id = 5 THEN CONCAT(Edition,' - ',sent_on) END AS Findexporters, CASE WHEN mailer_id = 6 THEN CONCAT(Edition,' - ',sent_on) END AS Dubaiexporters ,CASE WHEN mailer_id = 7 THEN CONCAT(Edition,' - ',sent_on) END AS IndiaExportNews FROM crm_support_inquiry) 

AS crm_support_inquiry, crm_inquiry_perticipant, crm_countries where crm_inquiry_perticipant.inquiry_id=crm_support_inquiry.inquiry_id and crm_countries.country_id=crm_inquiry_perticipant.country GROUP BY crm_support_inquiry.inquiry_id, crm_support_inquiry.event_id,crm_support_inquiry.event_name 

這爲它們在crm_perticipant_inquiry和crm_support_inquiry等於IDS的數據。

現在我想要crm_perticipant_inquiry中的所有id的數據，即使這些id的數據在crm_support_inquiry中不存在，它也必須返回null.I使用了正確的外連接並更改了查詢，如下所示，但我沒有得到所需的輸出。 plzz幫助!!

SELECT crm_countries.country_name as Country,crm_support_inquiry.event_name as Event, crm_inquiry_perticipant.company as Company,crm_inquiry_perticipant.contact_name ContactPerson,crm_inquiry_perticipant.email, 

GROUP_CONCAT(CONVERT(Expogroup, CHAR(200)) SEPARATOR '/') AS Expogroup,GROUP_CONCAT(CONVERT(Abdas, CHAR(200)) SEPARATOR '/') AS Abdas, GROUP_CONCAT(CONVERT(AfricaDetails, CHAR(200)) SEPARATOR '/') AS AfricaDetails, GROUP_CONCAT(CONVERT(Kenyadetails, CHAR(200)) SEPARATOR '/') AS Kenyadetails,GROUP_CONCAT(CONVERT(Findexporters, CHAR(200)) SEPARATOR '/') AS Findexporters,GROUP_CONCAT(CONVERT(Dubaiexporters, CHAR(200)) SEPARATOR '/') AS Dubaiexporters,GROUP_CONCAT(CONVERT(IndiaExportNews, CHAR(200)) SEPARATOR '/') AS IndiaExportNews FROM 

(SELECT inquiry_id,event_id,event_name,CASE WHEN mailer_id = 1 THEN CONCAT(Edition,' - ',sent_on) END AS Expogroup,CASE WHEN mailer_id = 2 THEN CONCAT(Edition,' - ',sent_on) END AS Abdas,CASE WHEN mailer_id = 3 THEN CONCAT(Edition,' - ',sent_on) END AS AfricaDetails,CASE WHEN mailer_id = 4 THEN CONCAT(Edition,' - ',sent_on) END AS Kenyadetails,CASE WHEN mailer_id = 5 THEN CONCAT(Edition,' - ',sent_on) END AS Findexporters, CASE WHEN mailer_id = 6 THEN CONCAT(Edition,' - ',sent_on) END AS Dubaiexporters ,CASE WHEN mailer_id = 7 THEN CONCAT(Edition,' - ',sent_on) END AS IndiaExportNews FROM crm_support_inquiry) 
AS crm_support_inquiry right outer join crm_inquiry_perticipant on crm_inquiry_perticipant.inquiry_id=crm_support_inquiry.inquiry_id, crm_countries where crm_countries.country_id=crm_inquiry_perticipant.country GROUP BY crm_support_inquiry.inquiry_id, crm_support_inquiry.event_id,crm_support_inquiry.event_name 

Answer 1

嘗試從查詢中刪除crm_countries表，看看你得到了所有的ID在crm_perticipant_inquiry。隨後可以添加crm_countries表。例如試試這個

SELECT crm_support_inquiry.event_name as Event, 
crm_inquiry_perticipant.company as Company, 
crm_inquiry_perticipant.contact_name ContactPerson, 
crm_inquiry_perticipant.email, 
GROUP_CONCAT(CONVERT(Expogroup, CHAR(200)) SEPARATOR '/') AS Expogroup,GROUP_CONCAT(CONVERT(Abdas, CHAR(200)) SEPARATOR '/') AS Abdas, GROUP_CONCAT(CONVERT(AfricaDetails, CHAR(200)) SEPARATOR '/') AS AfricaDetails, GROUP_CONCAT(CONVERT(Kenyadetails, CHAR(200)) SEPARATOR '/') AS Kenyadetails,GROUP_CONCAT(CONVERT(Findexporters, CHAR(200)) SEPARATOR '/') AS Findexporters,GROUP_CONCAT(CONVERT(Dubaiexporters, CHAR(200)) SEPARATOR '/') AS Dubaiexporters,GROUP_CONCAT(CONVERT(IndiaExportNews, CHAR(200)) SEPARATOR '/') AS IndiaExportNews FROM 

(SELECT inquiry_id,event_id,event_name,CASE WHEN mailer_id = 1 THEN CONCAT(Edition,' - ',sent_on) END AS Expogroup,CASE WHEN mailer_id = 2 THEN CONCAT(Edition,' - ',sent_on) END AS Abdas,CASE WHEN mailer_id = 3 THEN CONCAT(Edition,' - ',sent_on) END AS AfricaDetails,CASE WHEN mailer_id = 4 THEN CONCAT(Edition,' - ',sent_on) END AS Kenyadetails,CASE WHEN mailer_id = 5 THEN CONCAT(Edition,' - ',sent_on) END AS Findexporters, CASE WHEN mailer_id = 6 THEN CONCAT(Edition,' - ',sent_on) END AS Dubaiexporters ,CASE WHEN mailer_id = 7 THEN CONCAT(Edition,' - ',sent_on) END AS IndiaExportNews FROM crm_support_inquiry) 
AS crm_support_inquiry 
    right outer join crm_inquiry_perticipant on crm_inquiry_perticipant.inquiry_id=crm_support_inquiry.inquiry_id 
GROUP BY crm_support_inquiry.inquiry_id, 
crm_support_inquiry.event_id, 
crm_support_inquiry.event_name;