计算记录连接问题和答案表的记录 [英] count records joining questions and answers tables

问题描述

我有两个表格，想算一下已解决的问题:

I have two tables and would like to count solved questions:

表格:问题

id   title  solved_answer_id
174  Title1 0
172  Title2 45
173  Title3 0
175  Title4 49 

表格:答案

id  created_by question_id
49  953        175
47  907        173
48  906        173 
46  907        172
45  906        172

也许有人知道如何计算用户为953创建的答案的已解决问题(solved_answer_id> 0)?

May be someone know how to count solved questions (solved_answer_id>0) for answer created_by user: 953?

谢谢！

P.S结果将是:上面的情况是1(solved_answer_id = 49)...

P.S Result will be: 1 for the case above (solved_answer_id = 49)...

推荐答案

select count(q.id) as cnt
from questions q
join answers a on a.question_id = q.id
where q.solved_answer_id > 0
and a.created_by = 953

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