Self Doubt

Question

Let R (ABCD) and S(DEF). D is the foreign key in R that references primary key in S. Which of the following will not violation?

a. Insertion in R

b. Insertion in S

c. Deletion from R

d. Deletion from S 

Answer 1

Here D is foregin key in R...so it can have only those values which are in there in S...

Insertion in R may creates problem if D has value which is not in S......

Insertion in S will not be any problem..

Deletion from R also no problem...

but deletion from S may creates problem..as entry deleted from S may have an instance in R....

so out of all ..B and C will not create any problem 

Comments

Pls see Gate1997_6.10, isro2016-54.
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