sql找到最老的學生

SELECT s.sid, s.sname, COUNT(s.age) AS age 
FROM student s 
INNER JOIN enrolled e ON s.sid = e.sid 
INNER JOIN class c ON e.ccode = c.ccode 
INNER JOIN tutor t ON c.tid = t.tid 
WHERE s.programme = 'CIS' 
AND t.tname = 'Kathy Bond' 
GROUP BY s,sid, s.sname 
ORDER BY COUNT(s.age) DESC 
LIMIT 1;

我需要找到最老的獨聯體學生註冊凱西債券的類。這是我到目前爲止，它說它不能識別訂購操作員？這些都是表：sql找到最老的學生

類：

ccode | cname   | weekday | meets at | room | tid 
________________________________________________________________________ 
CIS166 | Intro to Comp | Tue  | 10:00:00 | MB300 | 1 
________________________________________________________________________ 
CIS177 | Maths   | Mon  | 15:00:00 | MB100 | 6 
________________________________________________________________________ 
CIS188 | Info Syst  | Thu  | 14:00:00 | MB230 | 5 
________________________________________________________________________ 
CIS199 | Intro to Java | Fri  | 10:00:00 | MB300 | 4 
________________________________________________________________________ 
CIS277 | Algorithmics | Thu  | 14:00:00 | MB200 | 2 
________________________________________________________________________ 
CIS288 | Database Syst | Mon  | 14:00:00 | MB142 | 1 
________________________________________________________________________ 
CIS297 | Web Design | Mon  | 16:00:00 | MB109 | 3 
________________________________________________________________________ 
CIS298 | C++   | Fri  | 10:00:00 | MB110 | 8

導師：

tid | tname 
_____________________ 
1 | Rob Hoffman 
_____________________ 
2 | James Butler 
_____________________ 
3 | Kathy Bond 
_____________________ 
4 | Theodora Stewart 
_____________________ 
5 | Mike Richie 
_____________________ 
6 | John Kay 
_____________________ 
7 | Mary Tregear 
_____________________ 
8 | Mark Robinson

已登記：

sid | ccode 
______________ 
211 | CIS288 
203 | CIS298 
214 | CIS297 
105 | CIS177 
215 | CIS297 
104 | CIS188 
210 | CIS297 
338 | CIS320 
102 | CIS177 
338 | CIS399 
204 | CIS288 
204 | CIS277 
102 | CIS199 
203 | CIS297 
105 | CIS199 
331 | CIS320 
202 | CIS299 
205 | CIS299 
210 | CIS298 
331 | CIS399 
321 | CIS399 
210 | CIS288 
210 | CIS277 
204 | CIS297 
321 | CIS320 
328 | CIS388 
327 | CIS388 
211 | CIS297 
333 | CIS399 
215 | CIS288 
104 | CIS199

學生：

sid | sname  | programme | level | age 
____________________________________________ 
101 | Lorry Ross | CS   | 1  | 18 
102 | Lydia Ken | CIS  | 1  | 18 
103 | Bob Chung | CS   | 1  | 18 
104 | Sonia Morris | CIS  | 1  | 18 
105 | Mark Poppy | CS   | 1  | 19 
106 | Megan Chi | IT   | 1  | 20 
218 | Diana McDon | IT   | 2  | 20 
219 | Nick Smith | IT   | 2  | 21

來源

2011-12-20 Sophie Williams

你爲什麼要計算年齡？ – 2011-12-20 15:40:53

你的SQL有一個拼寫錯誤：'GROUP BY s，sid，s.sname'應該是'GROUP BY s.sid，s.sname'（點不是逗號）。複製粘貼錯誤或實際錯誤？ – 2011-12-20 15:41:37

我不認爲你需要GROUP BY這裏。只要ORDER BY和LIMIT 1應該可以工作。試試這個：

SELECT s.sid, s.sname, s.age 
FROM student s 
INNER JOIN enrolled e ON s.sid = e.sid 
INNER JOIN class c ON e.ccode = c.ccode 
INNER JOIN tutor t ON c.tid = t.tid 
WHERE s.programme = 'CIS' 
AND t.tname = 'Kathy Bond' 
ORDER BY s.age DESC 
LIMIT 1

來源

2011-12-20 15:40:52

問題是這樣的： ORDER BY COUNT（s.age）DESC

它應該是： ORDER BY s.age DESC

你必須在計數SELECT語句的第一部分是它所屬的位置。

來源

2011-12-20 15:42:21 dmarges

'最古老'意味着MAX(age)。

來源

2011-12-20 15:48:15

sql找到最老的學生

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