Which of the following tuple relational calculus expression(s) is/are equivalent to? I. II. III. IV.
Question 2
Consider a relational table with a single record for each registered student with the following attributes. (1). Registration_Num: Unique registration number of each registered student (2). UID: Unique identity number, unique at the national level for each citizen (3). Bank Account_Num: Unique account number at the bank. A student can have multiple accounts or joint accounts. This attribute stores the primary account number. (4). Name: Name of the student (5). Hostel_Room: Room number of the hostel Which of the following options is INCORRECT?
Question 3
What is the optimized version of the relation algebra expression, where A1, A2 are sets of attributes in r with A1 ⊂A2 and F1, F2 are Boolean expressions based on the attributes in r?
Question 4
Let r be a relation instance with schema R = (A, B, C, D). We define r1 = ΠA, B, C (r) and r2 = ΠA.D (r). Let s = r1 * r2 where * denotes natural join. Given that the decomposition of r into r1 and r2 is lossy, which one of the following is TRUE?
Question 5
Consider the relation scheme R = (E, F, G, H, I, J, K, L, M, N) and the set of functional dependencies {{E, F} → {G}, {F} →{I, J}, {E, H} → {K, L}, {K} → {M}, {L} →{N}} on R. What is the key for R?
Question 6
An index is clustered, if
Question 7
A prime attribute of a relation scheme R is an attribute that appears
Question 8
Relation R with an associated set of functional dependencies, F, is decomposed into BCNF. The redundancy (arising out of functional dependencies) in the resulting set of relations is
Question 9
In ER models, which statement is not valid?
Question 10
Information about a collection of students is given by the relation studinfo(studId, name, sex). The relation enroll(studId, courseId) gives which student has enrolled for (or taken) what course(s). Assume that every course is taken by at least one male and at least one female student. What does the following relational algebra expression represent?
Question 11
Which among the following schedules exists if two transactions F1 and F 2 are serially conflicting? F 1 = K 1[X] L1[X] L 1[Y] F 2 = K 2[X] K 2[Y] L 2[Y] A = K 1[X] K 2[X] K 2[Y] L 1[X] L 1[Y] L 2[Y] B = K 1[X] K 2[X] K 2[Y] L 1[X] L 2[Y] L 1[Y] C = K 1[X] L 1[X] K 2[X] L 1[Y] K 2[Y] L 2[Y] D = K 1[X] K 2[Y] K 2[X] L 1[X] L 1[Y] L 2[Y]
Question 12
The following functional dependencies are given: AB→CD,AF→D,DE→F,C→G,F→E,G→A. Which one of the following options is false?
Question 13
In SQL, relations can contain null values, and comparisons with null values are treated as unknown. Suppose all comparisons with a null value are treated as false. Which of the following pairs is not equivalent?
Question 14
Let R and S be two relations with the following schema R(P, Q, R1, R2, R3) S (P, Q, S1, S2) where {P, Q} is the key for both schemas. Which of the following queries are equivalent? I. II. III. IV.
Question 15
In relational table, records of each aadhaar card information about a candidate is shown with attributes. Find the incorrect information? 1) Reference_Number: < Registration number for registered citizen 2) UID: Unique Identity number for each citizen 3) Account_Number: Unique account number. A citizen may have single or multiple accounts. This will keep primary account number 4) Name: Name of Citizen 5) Street_Number: Street number of citizen
Question 16
Here, Record Size= 32 Bytes Key Size= 6 Bytes
Consider a file of 16384 records. Each record is 32 bytes long and its key field is of size 6 bytes. The file is ordered on a non-key field, and the file organization is unspanned. The file is stored in a file system with block size 1024 bytes, and the size of a block pointer is 10 bytes. If the secondary index is built on the key field of the file, and a multi-level index scheme is used to store the secondary index, the number of first-level and second-level blocks in the multi-level index are respectively
Question 17
Given relations r(w,x) and s(y,z), the result of select distinct w,x from r, s is guaranteed to be same as r, provided
Question 18
Consider the table employee(empId, name, department, salary) and the two queries Q1,Q2 below. Assuming that department 5 has more than one employee, and we want to find the employees who get higher salary than anyone in thedepartment 5, which one of the statements is TRUE for any arbitrary employee table? Q1: Select e.empId From employee e Where not exists (Select * From employee s where s.department = “5” and s.salary>=e.salary) Q2: Select e.empId From employee e Where e.salary>Any (Select distinct salary From employee s Where s.department = “5”)
Question 19
Which is incorrect about Normal Forms?
Question 20
Given the following schema: employees (emp-id, first-name, last-name, hire-date, dept-id, salary) departments(dept-id, dept-name, manager-id, location-id) You want to display the last names and hire dates of all latest hires in their respective departments in the location ID 1700. You issue the following query: SQL>SELECT last-name, hire-date FROM employees WHERE (dept-id, hire-date) IN (SELECT dept-id, MAX(hire-date) FROM employees JOIN departments USING(dept-id) WHERE location-id = 1700 GROUP BY dept-id); What is the outcome?