select a.answer_number from answer_record a
inner join respondents c on a.respondents_number=c.respondents_number
inner join question b on a.question_number=b.question_number
where a.question_number=3 and b.question_p=1 and c.email='[email protected]';question_number、question_p、email都尝试建立索引,无效,查询时间为0.800左右。
咋办呢?
(SELECT * FROM answer_record WHERE question_number=3) a,
(SELECT * FROM question WHERE question_p=1) b,
(SELECT * from respondents WHERE email='[email protected]') c
WHERE a.question_number=b.question_number AND a.respondents_number=c.respondents_number;这样写,你看看会不会快些