在Mysql查询中，'GROUP BY'答案数和pending =''

Question

我有一个带有问题和答案的数据库（用户表以及以下查询的参考）表。我目前正在进行查询：

SELECT questions.*,COUNT(answers.questionid) as num_answers,users.username 
FROM questions LEFT JOIN answers ON questions.questionid = answers.questionid 
LEFT JOIN users ON questions.userid = users.userid 
WHERE questions.pending=''  
GROUP BY questions.questionid

以上查询可以解答我的问题详情，并计算了答案的数量。但是，我想在answer.pending =''中包含答案，这样当我得到答案的数量时，它只会显示已经批准的答案。

我需要在查询中添加什么才能使其正常工作？

Answer 1

根据您的问题，您需要答案。支持=''

SELECT questions.*,COUNT(answers.questionid) as num_answers,users.username 
FROM questions LEFT JOIN answers ON questions.questionid = answers.questionid 
LEFT JOIN users ON questions.userid = users.userid 
WHERE questions.pending='' and  answers.pending=''
GROUP BY questions.questionid

使用上面的查询

Answer 2

请尝试使用此代码，我认为你应该使用null而不是＆＃39;＆＃39;，

SELECT questions.*,COUNT(answers.questionid) as num_answers,users.username 
FROM questions LEFT JOIN answers ON questions.questionid = answers.questionid 
LEFT JOIN users ON questions.userid = users.userid 
WHERE questions.pending IS NULL and  answers.pending IS NULL
GROUP BY questions.questionid