Question

想象我有2张桌子，我想计算最畅销的艺术家：

音乐（id，title，条形码）

艺术家（条形码，艺术家）

SELECT COUNT(m.barcode) AS sells, m.barcode, artist
FROM music m
LEFT JOIN artists a
ON m.barcode = a.barcode
GROUP BY m.barcode ORDER BY sells DESC

此查询返回例如：

  sells    | barcode |   artist
 ---------------------------------
   1000        123       jdoe
    500        223       kloe
    100        321       jdoe

如何计算jdoe复杂地销售了1100首音乐？

提前感谢任何提示

Answer 1

您应该将group by从barcode更改为artist（并从barcode声明中删除select：

SELECT COUNT(m.barcode) AS sells, artist
FROM music m LEFT JOIN
     artists a
     ON m.barcode = a.barcode
GROUP BY artist
ORDER BY sells DESC;

Answer 2

SELECT COUNT(m.barcode) AS popular, m.barcode, a.artist, SUM(a.sell) 
FROM `music` AS m 
LEFT JOIN `artists` AS a 
ON (m.barcode = a.barcode)
WHERE a.artist = 'jdoe'
GROUP BY m.barcode 
ORDER BY `popular` DESC

MySQL嵌套计数语句

2 个答案: