Given the set of functional dependencies, (AB Þ CDE and A Þ E) , for relation scheme R = (A,B,C,D,E) we can infer the following:
A is a key for R
BE is a key for R
AB is a key for R
None of the above
Which of the following commands can be used to modify a tuple to other value?
INSERT INTO
UPDATE
ALTER TABLE ADD
SELECT …FOR UPDATE
For like predicate which of the following is true
i) % matches zero of more characters.
ii) _ matches exactly one character.
i-only
ii-only
Both of them
None of them
The functional dependency A Þ B for relation schema R(A,B,C,D) implies that
No two tuples in R can have the same value for attribute A
Any two tuples in R that have the same value for B must have the same value for A
Any two tuples in R that have the same value for A must have the same value for B
No two tuples in R can have the same value for attribute B
Which of the following will display all the employees in department 90 and having a salary of at least $8000.00?
SELECT * FROM employees WHERE department_id = 90 , salary >= 8000;
SELECT * FROM employees WHERE department_id = 90 AND salary >= 8000;
SELECT * FROM employees WHERE department_id = 90 AND salary >= 8000.00;
SELECT * FROM employees WHERE department_id = 90 AND salary > 8000;
…………..defines the structure of a relation which consists of a fixed set of attribute-domain pairs.
Program
Instance
Super Key
Schema
Which of the following is not a binary operator in relational algebra?
Project
Assignment
Semi-Join
Join
Which of the following lines of the SELECT statement contains an error?
line 1
line 2
line 3
There are no errors- statement returns intended results
The ........ is used for creating and destroying table, indexes and other forms of structures.
transaction control language
data manipulation language
data definition language
data control language
A relation schema R is in 3rd normal form if
All attributes in R have atomic domains
Each nonprime attribute in R is fully dependent on every key
R satisfies 2nd normal form and no nonprime attribute of R is transitively dependent on the primary key
R contains only 3 keys