sql計數函數加入

Question

SELECT c.cname, COUNT(e.ccode) 
FROM class c 
INNER JOIN enrolled e ON e.ccode = c.ccode 
WHERE room = 'MB100' 
AND e.ccode = < 10; 

我試圖找到MB100房間裏有少於10名學生的課程名稱，我該怎麼辦？

Answer 1

你缺少group by c.cname，試試這個：

SELECT c.cname, COUNT(e.ccode) 
FROM class c 
INNER JOIN enrolled e ON e.ccode = c.ccode 
WHERE room = 'MB100' 
Group by c.cname 
Having e.ccode =< 10;