MySQL的嵌套計數聲明

Question

想象，我有2個表，我想計算出最暢銷的藝人：

• 音樂（ID，標題，條形碼）

• 藝術家（條形碼，藝術家）

  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 
  

該查詢返回如：

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

我該如何計算jdoe複雜地銷售1100首音樂？

預先感謝任何暗示

Answer 1

你應該改變你的group by從barcode到artist（從select語句中刪除barcode）：

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