MySQL的未知列在ON條款「useranswers.userid」

Question

我得到的錯誤「列未找到：1054未知列‘的條款’在‘useranswers.userid’」使用下面的MySQL代碼

SELECT COUNT(*) FROM kumianswers 
INNER JOIN users on useranswers.userid = users.id 
INNER JOIN kumiquestions on useranswers.questionid = kumiquestions.id 
WHERE login = '".$username."' and users.level <= 3 and categoryid = 1; 

有一個名爲'useranswers'的表，它確實有一個名爲'userid'的列，並且'users'表有'id'字段。這是對舊的代碼行進行的修改。我們必須重新制作表格以適應正在開發的新系統。舊的工作代碼是....

SELECT COUNT(*) AS total FROM answers 
INNER JOIN users on answers.ans_user = users.user_id 
INNER JOIN questions on answers.ans_question = questions.quest_id 
WHERE username = '".$username."' and ans_level <= 3 and quest_type = 1; 

Answer 1

你從kumianswers選擇與users和kumiquestions加盟，但你嘗試與一列從useranswers —你不加入一個表進行比較。