mysql - 將多個表加入到查詢中的計數

Question

我想從表中選擇列並根據另一個表的連接計數，我該怎麼做？

這是我寫我的數查詢：

SELECT COUNT(*) AS num_review FROM approved_reviews m, reviews u where 
    m.review_id_=u.id and u.item_id =? and m.approved=1 

，我想它加入到

select item_id, item_name, item_price from items ? 

我該怎麼辦呢？

Answer 1

select items.item_id, item_name, item_price, COALESCE(t.cnt ,0)   
from items join (
        SELECT u.item_id , COUNT(*) cnt 
        FROM approved_reviews m, reviews u 
        WHERE m.review_id_=u.id and m.approved=1 
        GROUP BY u.item_id 
       ) t on items.item_id = t.item_id 

Answer 2

select * 
from 
(SELECT COUNT(*) AS num_review, u.item_id FROM approved_reviews m, reviews u where 
    m.review_id_=u.id and u.item_id =? and m.approved=1 group by u.item_id) count_sub, 
(select item_id, item_name, item_price from items) item_sub 
where item_sub.item_id = count_sub.item_id