a) Consider a relation R=(A,B,C,D) with the following instance: A B C D 1 1 2 3
ID: 3698962 • Letter: A
Question
a) Consider a relation R=(A,B,C,D) with the following instance:
A
B
C
D
1
1
2
3
1
2
2
3
1
3
2
3
2
4
5
6
3
6
7
8
Which of the following function dependencies are satisfied? Why or How?
1. A ---> B
2. A ---> CD
3. C --> D
b) The SQL like operator is case sensitive, but the lower () function on strings can be used to perform case insensitive matching. To show how, write a query that finds departments whose names contain the string “sci” as a substring, regardless of the case.
NOTE: PLEASE Writing is not recommended by hand
A
B
C
D
1
1
2
3
1
2
2
3
1
3
2
3
2
4
5
6
3
6
7
8
Explanation / Answer
a.) 1.) Since for same values of A, we are having different values of B. Therefore, A--> B is not satisfied.
2.) Since for each unique value of A, there is a different value of CD, therefore given relation is satisfiable.
3.) Since for each unique value of C, there is a different value of D, therefore given relation is satisfiable.
b.) Select Dept_name
From Department
Where lower(Dept_name) like '%sci% ;
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