-1
基础数据模型:http://i.imgur.com/WKWBDd8.jpgMYSQL MULTI JOINS with COUNTS
嗨,thx求救!
我希望做一个查询来获取的问题数(计数),并从课程答案的数目,
SELECT
courses.name,
courses.description,
courses.digest,
courses.views,
categories.icon,
COUNT(answers.id),
COUNT(problems.id)
FROM
courses
INNER JOIN
topics ON topics.id = courses.topics_id
INNER JOIN
categories ON categories.id = topics.categories_id
LEFT JOIN
problems ON problems.courses_id = courses.id
LEFT JOIN
answers ON answers.problems_id = problems_id
WHERE
courses.accounts_id = 1
GROUP BY courses.id
但是,这是行不通的任何想法?
THX
是错误信息还是意外行为分类?如果没有,请与我们分享。 – Shadow
可能是一个拼写错误,但在你最后一次加入时,你正在执行'answers.problems_id = problems_id'这是正确的吗?应该是problems.id吗? – Matt