複雜MySQL查詢它是

Question

我有一個answers表（ans_id，question_id，ans_date）和answers_votes表（vote_id，USER_ID，ans_id，表決= 1或-1）。

我該如何從答案中選擇有大總和（投票）今天發佈的投票。這意味着今天的日期在ans_date。

Answer 1

select a.ans_id 
    , a.question_id 
    , a.ans_date 
    , (select sum(vote) from answers_votes where ans_id = a.ans_id) as points 
    , (select count(*) from answers_votes where ans_id = a.ans_id and vote = 1) as up_votes 
    , (select count(*) from answers_votes where ans_id = a.ans_id and vote = -1) as down_votes 
    from answers a 
where date(a.ans_date) = date(now()) 
order by points desc 

雖然現在這將使該points值有些多餘。它可以像計算up_votes - down_votes一樣計算 - 只要投票總是隻值1分或上下。

Answer 2

事情是這樣的：

select answers.ans_id, count(*) as nb_votes 
from answers 
    inner join answers_votes on answers_votes.ans_id = answers.ans_id 
where answers.ans_date = curdate() 
group by answers.ans_id 
order by count(*) desc 
limit 10 

應該給你10個回答說有得票最多，而今天已經創建了。

如果您需要更多或更少的10，您可以更改limit子句中的值。

沒有測試過，因爲我沒有你的數據庫 - 因此可能包含了一些錯誤......