如何在MySQL中選擇所有類別並計算每個類別文章的數量

Question

類別表：

id, name
---------
1   cat1
2   cat2
3   cat3 
4   cat4

文章表：

id, cid, title
--------------
1   1    title1
2   3    title2
3   1    title3
4   2    title4   

如何在MySQL中選擇所有類別並計算每個類別文章的數量？ 我需要一個mysql查詢，該查詢將選擇所有類別和屬於每個類別的商品總數，並按類別ID進行排序。

預期輸出表：

+-------+-------+    
|  name | count |    
+-------+-------+    
|  cat1 |     2 |    
|  cat2 |     1 |    
|  cat3 |     1 |  
|  cat4 |     0 |  
+-------+-------+

Answer 1

SELECT
    c.`name`,
    COUNT(a.cid) AS `count`
FROM
    categories c
    LEFT JOIN article a ON c.id = a.cid
GROUP BY
    c.`name`
ORDER BY
    c.`name`

Answer 2

嘗試這個：

SELECT c.`name`, count(a.cid) as count FROM category
LEFT JOIN article
ON c.id = a.cid
GROUP BY a.cid

Answer 3

select c.name,count(b.title)count from category a, article b where c.id = a.cid group by c.name order by a.cid;

Answer 4

我希望這會起作用。 請檢查。

select
    Category.name.
    ifnull(count(Article.cid),0) as count
FROM
    Category
LEFT JOIN
    Article 
on
    Article.cid=Category.id
group by
    Category.Id 

Answer 5

您也可以使用子查詢，例如

SELECT c.name,(select count(*) from article where cid = c.id) as count  FROM cat c WHERE 1 GROUP BY c.id