內有三個表

Question

我有我的數據庫三個表加入：評論，地標，用戶，我想從每個表中的一些屬性，我試着用下面的查詢，但沒有什麼retrived，這是我的3個表

user (userid,firstName,lastName) 
comment (userid,L_ID,review) 
landmarks (L_ID,Title) 

用戶和用戶標識 評論，並與地標上L_ID

$q = mysqli_query($con,"SELECT l.*,c.id,c.review,CONCAT(u.firstName,' ',u.lastName) name FROM landmarks l inner join comment c on l.L_ID on c.L_ID inner join users u on u.userid=c.userid WHERE ".(isset($userid) ? "c.userid=$userid" : (isset($landmarkid) ? "c.L_ID=$landmarkid" : ""))." ORDER BY c.id"); 

Answer 1

發表評論我相信你有你的「內加入註解C1」開部分錯誤

SELECT l.*,c.id,c.review,CONCAT(u.firstName,' ',u.lastName) name 
FROM landmarks l 
inner join comment c 
    on l.L_ID 
    on c.L_ID 
inner join users u 
    on u.userid=c.userid 
WHERE ".(isset($userid) ? "c.userid=$userid" : (isset($landmarkid) ? "c.L_ID=$landmarkid" : ""))." 
ORDER BY c.id 

我相信你想要的是

SELECT l.*,c.id,c.review,CONCAT(u.firstName,' ',u.lastName) name 
FROM landmarks l 
inner join comment c 
    on c.L_ID = l.L_ID 
inner join users u 
    on u.userid=c.userid 
WHERE ".(isset($userid) ? "c.userid=$userid" : (isset($landmarkid) ? "c.L_ID=$landmarkid" : ""))." 
ORDER BY c.id