The Gateway to Computer Science Excellence
First time here? Checkout the FAQ!
x
0 votes
130 views

asked in Databases by (193 points) | 130 views
0

should be cid

0
it should be ssn ...because Professors are in full participation ..and relation is 1 to 1 ...

correct me if  i am wrong ...??
0
take the sample example and realize
0

course dont have total participation ...so what will you put in front of CID in tuple ??please help @ Shaik Masthan

0

if you want to take ssn as key then two tables required

if you make cid as key then only one table is sufficient....

The one table look like as (cid,Cname,ssn,name) 

which cid doesn't map to ssn ===> put NULL

check this https://gateoverflow.in/218954/what-an-interesting-dbms-question

0

what is causing the problem if we take ssn as the key ? all in one table

@Shaik+Masthan

0
@daksirp,

Then how could you find the courses which are not participating in the relation?
0

we will make ssn as the key, <ssn, name, cid, cname>

wherever courses is not participating in relation corresponding to ssn, we will put NULL.

by seeing NULL, we come to know it is not participating in relation.

its my view, correct me if im wrong

0
You want to put null in ssn?

Note that ssn is key, it cannot have null or duplicate values
0
noo, we will put NULL in courses, if courses is not participating, then we will put NULL in courses.
+1
Brother

Let assume professor table contains

1 A

2 B

Courses table contains

101 java

102 php

103 dbms

Now assume

101 map to 1

102 map to 2

Now give your table which contains ssn as key
0
yaa, now understood, with this my other doubts are also cleared :)
0
That's why I commented that " take examples you can realise"
0
yaa :)
0
What is the relationship type (and which side has many , is its 1:m)?
0

@smsubham, it is 1:1 relationship, having full participation on Professor entity side.

Please log in or register to answer this question.

Related questions

Quick search syntax
tags tag:apple
author user:martin
title title:apple
content content:apple
exclude -tag:apple
force match +apple
views views:100
score score:10
answers answers:2
is accepted isaccepted:true
is closed isclosed:true
49,540 questions
54,099 answers
187,269 comments
71,006 users