优化论坛查询

Question

你们能帮我优化这个查询吗？什么是更有效的方法来做到这一点？

SELECT *, ( 
     SELECT COUNT(id) FROM post WHERE created > 1288953377 AND topic_id = topic.id 
    ) AS post_today FROM topic 

Answer 1

我想这是你需要什么，

SELECT Col1,Col2,Col3, Count(id) from Topic 
LEFT JOIN post on topic_id = topic.id 
where created > 1288953377 
group by id,Col1,Col2,Col3