選擇離開加入

Question

我的PHP會話：

$get_user = $_SESSION['id']; //id of the user that logged in 

我的查詢是：

$query_select = "SELECT i.users_id,s.seen, CONCAT_WS(' ', i.users_fname, i.users_lname) 
AS full_name 
FROM tbl_request AS f 
LEFT JOIN tbl_usersinfo AS i ON i.users_id = f.user_id 
LEFT JOIN tbl_status AS s ON s.user_id = f.user_id 
WHERE (f.user_id = $get_user || f.another_user = $get_user) && f.status = 'accepted' 
GROUP BY full_name ORDER BY seen DESC 

tbl_request：

user_id another_user status 
1    2  'accepted' 
1    5  'accepted' 
3    1   'waiting' 
4    1   'accepted' 

tbl_usersinfo

users_id users_fname  users_lname 
1    michael   jackson 
2    michael   jordan 
3    bat    man 
4    will    smith 
5    sean    kingston 

tbl_status

user_id  seen 
1   'online' 
2   'offline' 
3   'online' 
4   'online' 
5   'offline' 

讓我們假設會話等於1，此查詢將導致到：

users_id full_name  seen 
4   will smith online 

它應該是：

users_id full_name   seen 
    2  michael jordan  offline 
    4  will smith   online 
    5  sean kingston  offline 

我想選擇所有的狀態即等於「接受」，但上述查詢僅在會話等於another_user時顯示。我希望我的查詢具有靈活性。例如，當會話等於user_id時，它應該選擇another_user，因爲那是他朋友的ID。

Answer 1

的問題是，在你的LEFT JOIN是你總是比作f.user_id，但它應該是f.user_id只有當你的$get_user是another_user列...以及在其他的方式一樣...我建議你改造完成查詢......

有很多方法可以做到這一點，但也許simplier將使用UNION：

SELECT i.users_id,s.seen, CONCAT_WS(' ', i.users_fname, i.users_lname) 
AS full_name 
FROM tbl_request AS f 
LEFT JOIN tbl_usersinfo AS i ON i.users_id = f.another_user 
LEFT JOIN tbl_status AS s ON s.user_id = f.another_user 
WHERE f.user_id = $get_user && f.status = 'accepted' 
UNION 
SELECT i.users_id,s.seen, CONCAT_WS(' ', i.users_fname, i.users_lname) 
AS full_name 
FROM tbl_request AS f 
LEFT JOIN tbl_usersinfo AS i ON i.users_id = f.user_id 
LEFT JOIN tbl_status AS s ON s.user_id = f.user_id 
WHERE f.another_user = $get_user && f.status = 'accepted' 
GROUP BY full_name ORDER BY seen DESC