| Design problem [message #285105] |
Mon, 03 December 2007 08:46  |
SRIVASUWIN
Messages: 45
Registered: October 2006
Location: TRICHY
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Member |
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Good day every body,
I have explained my desiging problem situation in below example.
eg:
patient
------
prac_id(pk)
location
-------
loc_id(fk)
course master
--------------
course_code(pk)
prac_id (fk)
loc_id(fk)
diploma master
--------------
deg_code(pk)
prac_id (fk)
loc_id (fk)
stud_trans
----------
stud_transid(pk)
deg_code(fk)
course_code(fk)
in this above tables stud_trans table contain two foreign key(deg_code and course_code) but
(i)some students have only deg_code
(ii)some students have only course_code
(iii) some students have both deg_code and course_code.
could u advice what is the way to design this deg_code and course_code within one table and also to satify
this 3 condition within one table.
- Thank you
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| Re: Design problem [message #285111 is a reply to message #285105] |
Mon, 03 December 2007 09:53  |
Frank
Messages: 7901
Registered: March 2000
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Senior Member |
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Are the two related? (deg and course)
If not, there is no point in storing those relationships in a single table.
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| Re: Design problem [message #285114 is a reply to message #285105] |
Mon, 03 December 2007 10:11 |
MarcL
Messages: 455
Registered: November 2006
Location: Connecticut, USA
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Senior Member |
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To expand on what Frank said, you probably need two student tables, one that is the student_master, and one that is the student_courses. Just a thought
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| Re: Design problem [message #285121 is a reply to message #285116] |
Mon, 03 December 2007 10:48 |
compcoder
Messages: 30
Registered: April 2007
Location: Maryland USA
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Member |
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Here is a very brief example. You have to explictly tell Oracle not to accept NULLS. The default is to allow NULLS.
CREATE TABLE STUDENT_TRANS
(
STUD_TRANSID NUMBER,
DEG_CODE NUMBER,
COURSE_CODE NUMBER
)
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