(SELECT s.sid, s.sname, e.ccode
FROM student s INNER JOIN enrolled e
ON s.sid = e.sid
WHERE s.programme = 'IT')
WHERE EXISTS
(SELECT c.ccode, c.tid
FROM class c INNER JOIN tutor t
ON c.tid = t.tid
WHERE t.tname = 'Hoffman');
这就是我到目前为止,虽然不工作。需要从在一类被称为霍夫曼导师招收学生表中获取IT学生的名字,都来自就读,阶级和导师表。 我在哪里错了?SQL连接4表
类:
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
导师:
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
已登记:
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
学生:
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
请向我们展示表结构(带有足以用于查询的字段)。现在,您的查询的两个部分没有链接的字段,并且很难建议它们存在的位置。 – Minras 2011-12-19 15:14:49