優化論壇查詢

Question

你們能幫我優化這個查詢嗎？什麼是更有效的方法來做到這一點？

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

Answer 1

我想這是你需要什麼，

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