Which one of the following statements is NOT correct about the B⁺ tree data structure used for creating an index of a relational database table?

Consider the following two statements about database transaction schedules:

I. Strict two-phase locking protocol generates conflict serializable schedules that are also recoverable.
II. Timestamp-ordering concurrency control protocol with Thomas Write Rule can generate view serializable schedules that are not conflict serializable.

Consider the following relations P(X,Y,Z), Q(X,Y,T) and R(Y,V).

How many tuples will be returned by the following relational algebra query?

          ∏x(σ(P.Y=R.Y ∧ R.V=V2)(P × R)) - ∏x(σ(Q.Y=R.Y ∧ Q.T>2)(Q × R))

A relational database contains two tables Student and Performance as shown below:

The primary key of the Student table is Roll_no. For the Performance table, the columns Roll_no. and Subject_code together from the primary key. Consider the SQL query given below:

       SELECT S.Student_name, sum (P.Marks)
       FROM Student S, Performance P
       WHERE P.Marks > 84
       GROUP BY S.Student_name;

The number of rows returned by the above SQL query is _____.

Let the set of functional dependencies F = {QR → S, R → P, S → Q} hold on a relation schema X = (PQRS). X is not in BCNF. Suppose X is decomposed into two schemas Y and Z, where Y = (PR) and Z = (QRS).

    I. Both Y and Z are in BCNF
   II. Decomposition of X into Y and Z is dependency preserving and lossless

In an Entity-Relationship (ER) model, suppose R is a many-to-one relationship from entity set E1 to entity set E2. Assume that E1 and E2 participate totally in R and that the cardinality of E1 is greater than the cardinality of E2.

Which one of the following is true about R?

Consider the following two tables and four queries in SQL.

Query 1:    SELECT B.isbn, S.copies
            FROM Book B INNER JOIN Stock S
            ON B.isbn = S.isbn;

Query 2:    SELECT B.isbn, S.copies
            FROM Book B LEFT OUTER JOIN Stock S
            ON B.isbn = S.isbn;

Query 3:    SELECT B.isbn, S.copies
            FROM Book B RIGHT OUTER JOIN Stock S
            ON B.isbn = S.isbn;

Query 4:    SELECT B.isbn, S.copies
            FROM Book B FULL OUTER JOIN Stock S
            ON B.isbn = S.isbn;

Which one of the queries above is certain to have an output that is a superset of the outputs of the other three queries?

Consider the following four relational schemas. For each schema, all non-trivial functional dependencies are listed. The underlined attributes are the respective primary keys.

Schema I: Registration(rollno, courses)
          Field ‘courses’ is a set-valued attribute containing the set of 
          courses a student has registered for.
          Non-trivial functional dependency
          rollno → courses

Schema II: Registration (rollno, coursid, email)
          Non-trivial functional dependencies:
          rollno, courseid → email
          email → rollno
 	
Schema III: Registration (rollno, courseid, marks, grade)
          Non-trivial functional dependencies:
          rollno, courseid, → marks, grade
          marks → grade
 	
Schema IV: Registration (rollno, courseid, credit)
          Non-trivial functional dependencies:
          rollno, courseid → credit
          courseid → credit

Which one of the relational schemas above is in 3NF but not in BCNF?

Consider the relations r(A, B) and s(B, C), where s.B is a primary key and r.B is a foreign key referencing s.B. Consider the query

Q: r⋈(σ_B<5(s))

Let LOJ denote the natural left outer-join operation. Assume that r and s contain no null values.

Which one of the following is NOT equivalent to Q?

The following functional dependencies hold true for the relational schema {V, W, X, Y, Z} :

V → W
VW → X
Y → VX
Y → Z

Which of the following is irreducible equivalent for this set of functional dependencies?

Consider a database that has the relation schema EMP (EmpId, EmpName, and DeptName). An instance of the schema EMP and a SQL query on it are given below.

The output of executing the SQL query is ___________.

Consider a database that has the relation schemas EMP(EmpId, EmpName, DeptId), and DEPT(DeptName, DeptId). Note that the DeptId can be permitted to a NULL in the relation EMP. Consider the following queries on the database expressed in tuple relational calculus.

(I) {t│∃u ∈ EMP(t[EmpName] = u[EmpName] ∧ ∀v ∈ DEPT(t[DeptId] ≠ v[DeptId]))}
(II) {t│∃u ∈ EMP(t[EmpName] = u[EmpName] ∧ ∃v ∈ DEPT(t[DeptId] ≠ v[DeptId]))}
(III) {t│∃u ∈ EMP(t[EmpName] = u[EmpName] ∧ ∃v ∈ DEPT(t[DeptId] = v[DeptId]))}

Which of the above queries are safe?

In a database system, unique timestamps are assigned to each transaction using Lamport’s logical clock. Let TS(T₁) and TS(T₂) be the timestamps of transactions T₁ and T₂ respectively. Besides, T₁ holds a lock on the resource R and T₂ has requested a conflicting lock on the same resource R. The following algorithm is used to prevent deadlocks in the database system assuming that a killed transaction is restarted with the same timestamp.

      
           if TS(T2)<TS(T1) then
                T1 is killed
           else T2 waits.

Assume any transaction that is not killed terminates eventually. Which of the following is TRUE about the database system that uses the above algorithm to prevent deadlocks?

Consider a database that has the relation schema CR(StudentName, CourseName). An instance of the schema CR is as given below.

The following query is made on the database.

         T1 ← πCourseName(σStudentName='SA'(CR))
         T2 ← CR ÷ T1

The number of rows in T2 is ____________.

An ER model of a database consists of entity types A and B. These are connected by a relationship R which does not have its own attribute. Under which one of the following conditions, can the relational table for R be merged with that of A?

In table T1, P is the primary key and Q is the foreign key referencing R in table T2 with on-delete cascade and on-update cascade. In table T2, R is the primary key and S is the foreign key referencing P in table T1 with on-delete set NULL and on-update cascade. In order to delete record 〈3,8〉 from table T1, the number of additional records that need to be deleted from table T1 is _________.

Two transactions T₁ and T₂ are given as

T₁: r₁(X)w₁(X)r₁(Y)w₁(Y)
T₂: r₂(Y)w₂(Y)r₂(Z)w₂(Z)

where r_i(V) denotes a read operation by transaction T_i on a variable V and w_i(V) denotes a write operation by transaction T_i on a variable V. The total number of conflict serializable schedules that can be formed by T₁ and T₂ is ____________.

Consider the following database table named top_scorer.

SELECT ta.player FROM top_scorer AS ta
WHERE ta.goals > ALL (SELECT tb.goals
                  FROM top_scorer AS tb
                  WHERE tb.country = 'Spain')
AND ta.goals > ANY (SELECT tc.goals
                  FROM top_scorer AS tc
                  WHERE tc.country = 'Germany')

The number of tuples returned by the above SQL query is _____.

In a B⁺ tree, if the search-key value is 8 bytes long, the block size is 512 bytes and the block pointer size is 2 bytes, then the maximum order of the B⁺ tree is _________.

Which of the following is NOT a superkey in a relational schema with attributes V, W, X, Y, Z and primary key VY?

NOT a part of the ACID properties of database transactions?

A database of research articles in a journal uses the following schema.

(VOLUME, NUMBER, STARTPAGE, ENDPAGE, TITLE, YEAR, PRICE)

The primary key is (VOLUME, NUMBER, STARTPAGE, ENDPAGE) and the following functional dependencies exist in the schema.

(VOLUME, NUMBER, STARTPAGE, ENDPAGE) → TITLE
(VOLUME, NUMBER) → YEAR
(VOLUME, NUMBER, STARTPAGE, ENDPAGE) → PRICE

The database is redesigned to use the following schemas.

(VOLUME, NUMBER, STARTPAGE, ENDPAGE, TITLE, PRICE)
(VOLUME, NUMBER, YEAR)

Which is the weakest normal form that the new database satisfies, but the old one does not?

Consider the following two phase locking protocol. Suppose a transaction T accesses (for read or write operations), a certain set of objects{O₁,...,O_k}. This is done in the following manner:

Step1. T acquires exclusive locks to O₁,...,O_k in increasing order of their addresses.
Step2. The required operations are performed.
Step3. All locks are released.

This protocol will

B⁺ Trees are considered BALANCED because

Suppose a database schedule S involves transactions T₁, ..., T_n. Construct the precedence graph of S with vertices representing the transactions and edges representing the conflicts. If S is serializable, which one of the following orderings of the vertices of the precedence graph is guaranteed to yield a serial schedule?

Consider the following database schedule with two transactions, T₁ and T₂.

S = r₂(X); r₁(X); r₂(Y); w₁(X); r₁(Y); w₂(X); a₁; a₂

where r_i(Z) denotes a read operation by transaction T_i on a variable Z, w_i(Z) denotes a write operation by T_i on a variable Z and a_i denotes an abort by transaction T_i.

Which one of the following statements about the above schedule is TRUE?

Consider the following database table named water_schemes :

The number of tuples returned by the following SQL query is _________.

with total(name, capacity) as
   select district_name, sum(capacity)
   from water_schemes
   group by district_name
with total_avg(capacity) as
   select avg(capacity)
   from total
select name
   from total, total_avg
   where total.capacity ≥ total_avg.capacity

SELECT S. Student_Name, sum(P.Marks)
     FROM Student S, Performance P
     WHERE S.Roll_No = P.Roll_No
     GROUP BY S.Student_Name

F = {
       {P, R} → {S,T},  
       {P, S, U} → {Q, R}
    }

  Cinema (theater, address, capacity)

SELECT P1. address
FROM Cinema P1

    S1: A foreign key declaration can always 
        be replaced by an equivalent check
        assertion in SQL.
    S2: Given the table R(a,b,c) where a and
        b together form the primary key, the 
        following is a valid table definition.
        CREATE TABLE S (
            a INTEGER,
            d INTEGER,
            e INTEGER,
            PRIMARY KEY (d),
            FOREIGN KEY (a) references R)

  S1: Every table with two single-valued 
      attributes is in 1NF, 2NF, 3NF and BCNF.

  S2: AB->C, D->E, E->C is a minimal cover for 
      the set of functional dependencies 
      AB->C, D->E, AB->E, E->C.

     employees(emp-id, first-name, last-name, hire-date, dept-id, salary)
     departments(dept-id, dept-name, manager-id, location-id)

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?

    select * from R where a in (select S.a from S)

T1: read (P) ;
    read (Q) ;
    if P = 0 then Q : = Q + 1 ;
    write (Q) ;
T2: read (Q) ;
    read (P) ;
    if Q = 0 then P : = P + 1 ;
    write (P) ;

SELECT A.id 
FROM   A 
WHERE  A.age > ALL (SELECT B.age 
                    FROM   B 
                    WHERE  B. name = "arun")

1. Registration_Num: Unique registration number
   of each registered student
2. UID: Unique identity number, unique at the 
   national level for each citizen
3. BankAccount_Num: Unique account number at
   the bank. A student can have multiple accounts
   or join accounts. This attribute stores the 
   primary account number.
4. Name: Name of the student
5. Hostel_Room: Room number of the hostel 
Which one of the following option is INCORRECT?

Borrower    Bank_Manager   Loan_Amount
 Ramesh      Sunderajan     10000.00
 Suresh      Ramgopal       5000.00
 Mahesh      Sunderajan     7000.00

SELECT Count(*) 
FROM  ( ( SELECT Borrower, Bank_Manager 
          FROM Loan_Records) AS S 
          NATURAL JOIN ( SELECT Bank_Manager, Loan_Amount 
                         FROM Loan_Records) AS T );

SELECT Y FROM T WHERE X=7;

Table: Passenger
pid   pname   age
-----------------
 0    Sachin   65
 1    Rahul    66
 2    Sourav   67
 3    Anil     69

Table : Reservation
pid  class  tid
---------------
 0    AC   8200
 1    AC   8201
 2    SC   8201
 5    AC   8203
 1    SC   8204
 3    AC   8202

SLECT pid
FROM Reservation ,
WHERE class ‘AC’ AND
    EXISTS (SELECT *
       FROM Passenger
       WHERE age > 65 AND
       Passenger. pid = Reservation.pid)

B -> A
A -> C

A → B, B → C,
C → D and D → B. 

The decomposition of R into 
(A, B), (B, C), (B, D)

(S1)	2RA	2WA	3RC	2WB	3WA	3WC	1RA	1RB	1WA	1WB
(S2)	3RC	2RA	2WA	2WB	3WA	1RA	1RB	1WA	1WB	3WC
(S3)	2RA	3RC	3WA	2WA	2WB	3WC	1RA	1RB	1WA	1WB

Consider a selection of the form σ_A≤100(r), where r is a relation with 1000 tuples. Assume that the attribute values for A among the tuples are uniformly distributed in the interval [0, 500]. Which one of the following options is the best estimate of the number of tuples returned by the given selection query ?

• • b-Schema = (b-name, b-city, assets)
  • a-Schema = (a-num, b-name, bal)
  • d-Schema = (c-name, a-number)

  1. T1 start
  2. T1 B old=12000 new=10000
  3. T1 M old=0 new=2000
  4. T1 commit
  5. T2 start
  6. T2 B old=10000 new=10500
  7. T2 commit

Consider the relation enrolled(student, course) in which (student, course) is the primary key, and the relation paid(student, amount), where student is the primary key. Assume no null values and no foreign keys or integrity constraints. Assume that amounts 6000, 7000, 8000, 9000 and 10000 were each paid by 20% of the students. Consider these query plans (Plan 1 on left, Plan 2 on right) to "list all courses taken by students who have paid more than x".

A disk seek takes 4ms, disk data transfer bandwidth is 300 MB/s and checking a tuple to see if amount is greater than x takes 10 micro-seconds. Which of the following statements is correct?

AB   CD, AF   D, DE   F, C  G , F   E, G   A

Query1:
  select A.customer, count(B.customer)
  from account A, account B
  where A.balance <=B.balance
  group by A.customer

Query2:
  select A.customer, 1+count(B.customer)
  from account A, account B
  where A.balance < B.balance
  group by A.customer

1. Query1 will produce the same row set as Query2 for 
   some but not all databases.
2. Both Query1 and Query2 are correct implementation 
   of the specification
3. Query1 is a correct implementation of the specification
   but Query2 is not
4. Neither Query1 nor Query2 is a correct implementation
   of the specification
5. Assigning rank with a pure relational query takes 
   less time than scanning in decreasing balance order 
   assigning ranks using ODBC.

Query1: select student from enrolled where 
        student in (select student from paid)
Query2: select student from paid where 
        student in (select student from enrolled)
Query3: select E.student from enrolled E, paid P 
         where E.student = P.student
Query4:  select student from paid where exists
        (select * from enrolled where enrolled.student
         = paid.student)

Consider the relations r₁(P, Q, R) and r₂(R, S, T) with primary keys P and R respectively. The relation r₁ contains 2000 tuples and r₂ contains 2500 tuples. The maximum size of the join r₁⋈ r₂ is :

1. Relational algebra
2. Tuple relational calculus restricted to safe expressions
3. Domain relational calculus restricted to safe expressions

In a database file structure, the search key field is 9 bytes long, the block size is 512 bytes, a record pointer is 7 bytes and a block pointer is 6 bytes. The largest possible order of a non-leaf node in a B⁺ tree implementing this file structure is

  select title
  from book as B
  where (select count(*)
     from book as T
     where T.price > B.price) < 5

A   C
-----
2   4
3   4
4   3
5   2
7   2
9   5
6   4

select hostel
from student natural join hobby
where marks > = 75 and roll between 2000 and 3000;

Select distinct STMP.supplierid
From Supply as STMP
Where not unique (Select ITMP.supplierid
                  From Inventory, Supply as ITMP
                  Where STMP.supplierid = ITMP.supplierid
                  And ITMP.itemcode = Inventory.itemcode
                  And Inventory.warehouse = 'Nagpur');

Let R₁ (A, B, (D)) and R₂ (D, E) be two relation schema, where the primary keys are shown underlined, and let C be a foreign key in R₁ referring to R₂. Suppose there is no violation of the above referential integrity constraint in the corresponding relation instances r₁ and r₂. Which one of the following relational algebra expressions would necessarily produce an empty relation? 

Consider the following entity relationship diagram (ERD), where two entities E1 and E2 have a relation R of cardinality 1 : m.

The attributes of E1 are A11, A12 and A13 where A11 is the key attribute. The attributes of E2 are A21, A22 and A23 where A21 is the key attribute and A23 is a multi-valued attribute. Relation R does not have any attribute. A relational database containing minimum number of tables with each table satisfying the requirements of the third normal form (3NF) is designed from the above ERD. The number of tables in the database is

Insert into department values (1, 'Mathematics')
Insert into department values (2, 'Physics')
Insert into student values (l, 'Navin', 1)
Insert into student values (2, 'Mukesh', 2)
Insert into student values (3, 'Gita', 1)

Select * from student, department

A relation Empdtl is defined with attributes empcode (unique), name, street, city, state and pincode. For any pincode, there is only one city and state. Also, for any given street, city and state, there is just one pincode. In normalization terms, Empdtl is a relation in

Update T1 set marks = marks + 5
Select avg(marks) from T1

1. update Student set Dept_id = Null where Roll_on = 1
   1. update Department set Dept_id = Null where Dept_id = 1

Consider a table T in a relational database with a key field K. A B-tree of order p is used as an access structure on K, where p denotes the maximum number of tree pointers in a B-tree index node. Assume that K is 10 bytes long; disk block size is 512 bytes; each data pointer P_D is 8 bytes long and each block pointer P_B is 5 bytes long. In order for each B-tree node to fit in a single disk block, the maximum value of p is