在MySQL中處理日期？

Question

編輯：改變對不起，我嘗試處理MySQL的DATETIME值， 這是我的MySQL查詢的整個問題：

$result="SELECT u.username, u.picture, m.id, m.user_note, m.reply_id, m.reply_name, m. m.dt 
FROM relationships r, notes m, user u 
WHERE m.user_id = r.leader 
AND r.leader = u.user_id 
AND r.listener ='".$_SESSION['user_id']."' 
UNION 
SELECT username, picture, id, user_note, reply_id, reply_name, dt 
FROM user u, notes b 
WHERE u.user_id = b.user_id 
AND b.user_id = '".$_SESSION['user_id']."' 
AND dt < '".$lastmsg."' 
ORDER BY dt DESC 
LIMIT 10 "; 

我嘗試從該查詢不是「$ lastmsg」年長找到行，而不是$ lastmsg本身，我想過使用少於但不等於操作符！我不知道這是愚蠢的！

查詢的工作原理，但它的錯誤信息！

Answer 1

您只限制UNION下半部分的日期。試試這個：

SELECT u.username, u.picture, m.id, m.user_note, m.reply_id, m.reply_name, m.dt 
FROM relationships r, notes m, user u 
WHERE m.user_id = r.leader 
AND r.leader = u.user_id 
AND r.listener ='".$_SESSION['user_id']."' 
AND m.dt < '".$lastmsg."' 
UNION 
SELECT username, picture, id, user_note, reply_id, reply_name, dt 
FROM user u, notes b 
WHERE u.user_id = b.user_id 
AND b.user_id = '".$_SESSION['user_id']."' 
AND dt < '".$lastmsg."' 
ORDER BY dt DESC 
LIMIT 10 

Answer 2

難道不應該着眼於日期查詢片段是

AND dt > '".$lastmsg."' 

？