結合2個查詢的MySQL

Question

有人可以幫我組合下面的2個查詢嗎？目標是在php中創建Speaker和Organizer變量（也在下面）。謝謝！

$query= " 
SELECT srMeet.mOrg, srMeet.mSpeaker, users.uID, users.uFirst, users.uLast 
FROM srMeet 
INNER JOIN users 
ON users.uID = srMeet.mSpeaker"; 

$query= " 
SELECT srMeet.mOrg, srMeet.mSpeaker, users.uID, users.uFirst, users.uLast 
FROM srMeet 
INNER JOIN users 
ON users.uID = srMeet.mOrg"; 


$Speaker = $row['uFirst'] . " " . $row['uLast']; 

$Organizer = $row['uFirst'] . " " . $row['uLast']; 

Answer 1

假設一個滿足了一個揚聲器，你可以使用連接來獲得在一行中的相遇細節一個組織者。

$query= "SELECT srMeet.mOrg, 
      srMeet.mSpeaker, 
      UserSpeaker.uID AS SpeakerUid, 
      UserSpeaker.uFirst AS SpeakerFirst, 
      UserSpeaker.uLast AS SpeakerLast, 
      UserOrganizer.uID AS OrganizerUid, 
      UserOrganizer.uFirst AS OrganizerFirst, 
      UserOrganizer.uLast AS OrganizerLast 
     FROM srMeet 
     INNER JOIN users UserSpeaker 
     ON UserSpeaker.uID = srMeet.mSpeaker 
     INNER JOIN users UserOrganizer 
     ON UserOrganizer.uID = srMeet.mOrg"; 

Answer 2

你爲什麼不使用UNION

$query= " 
SELECT srMeet.mOrg, srMeet.mSpeaker, users.uID, users.uFirst, users.uLast 
FROM srMeet 
INNER JOIN users 
ON users.uID = srMeet.mSpeaker 
UNION 
SELECT srMeet.mOrg, srMeet.mSpeaker, users.uID, users.uFirst, users.uLast 
FROM srMeet 
INNER JOIN users 
ON users.uID = srMeet.mOrg" 

Answer 3

你可以參加在查詢同一個表多次使用AS給他們的別名。 AS關鍵字實際上是可選的，但我始終將其作爲對自己的說明。

這裏的INNER JOIN表示每個會議必須同時具有組織者和發言者。如果有機會在沒有組織者或演講者的情況下舉行會議，則可能需要使用LEFT OUTER JOIN s並執行一些操作來處理NULL值。

SELECT CONCAT(s.uFirst, ' ', s.uLast) AS speaker, 
    CONCAT(o.uFirst, ' ', o.uLast) AS organizer 
FROM srMeet 
INNER JOIN users AS s 
ON users.uID = srMeet.mSpeaker 
INNER JOIN users AS o 
ON users.uID = srMeet.mOrg; 


$Speaker = $row['speaker']; 

$Organizer = $row['organizer'];