內部連接語句上的mysql語法錯誤

Question

我想從兩個表中獲取最后5行。

這是我執行的mysql語句：

"SELECT title, thread_id
FROM threads AS t1
JOIN ON comments AS c1 ON t1.user_id = c1.user_id
 WHERE t1.user_id=".$userID
." OR c1.user_id=".$userID.
" ORDER BY thread_id DESC
LIMIT 0,5"

這是錯誤：

您的SQL語法有誤； 請檢查與您的MySQL服務器版本相對應的手冊，以獲取正確的語法，以在“在ON注釋AS c1上t1.user_id = c1.user_id WHERE t1.user_id = 1 OR c1附近使用注釋”附近使用。 在第3行

我究竟做錯了什么？！？

Answer 1

你有多余的ON之前comments 。

Answer 2

沒有類似JOIN ON東西應該是JOIN或INNER JOIN ， LEFT JOIN 。 像這樣的東西：

"SELECT title, thread_id
FROM threads AS t1
JOIN comments AS c1 ON t1.user_id = c1.user_id
 WHERE t1.user_id=".$userID
." OR c1.user_id=".$userID.
" ORDER BY thread_id DESC
LIMIT 0,5"

Answer 3

刪除第3行中多余的ON。 它將起作用。

"SELECT title, thread_id
FROM threads AS t1
JOIN comments AS c1 ON t1.user_id = c1.user_id
 WHERE t1.user_id=".$userID
." OR c1.user_id=".$userID.
" ORDER BY thread_id DESC
LIMIT 0,5"