Which level of locking provides the highest degree of concurrency in a relational database?

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

A relational database contains two tables student and department in which student table has columns roll_no, name and dept_id and department table has columns dept_id and dept_name. The following insert statements were executed successfully to populate the empty tables:

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

A table T1 in a relational database has the following rows and columns:

 roll no.	 marks
    1	          10
    2	          20
    3	          30
    4	         Null 

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

Consider two tables in a relational database with columns and rows as follows:

Table: Student
ROLL_NO	  NAME	DEPT_ID
   1	  ABC	   1
   2	  DEF	   1
   3	  GHI	   2
   4	  JKL	   3
Table: Department
DEPT_ID	DEPT_NAME
   1	   A
   2	   B
   3	   C 

(i)  update Student set Dept_id = Null 
     where Roll_on = 1
(ii) 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

Consider a relational database containing the following schemas.

The primary key of each table is indicated by underlying the constituent fields.

SELECT s.sno, s.sname
FROM Suppliers s, Catalogue c
WHERE s.sno = c.sno AND
              Cost > (SELECT AVG (cost)
                      FROM Catalogue
                      WHERE pno = ‘P4’
                      GROUP BY pno);

The number of rows returned by the above SQL query is

Which one of the following is used to represent the supporting many-one relationships of a weak entity set in an entity-relationship diagram?

Consider a schedule of transactions T₁ and T₂:

Here, RX stands for “Read(X)” and WX stands for “Write(X)”. Which one of the following schedules is conflict equivalent to the above schedule?

Consider a relational table R that is in 3NF, but not in BCNF. Which one of the following statements is TRUE?

Consider a database implemented using B+ tree for file indexing and installed on a disk drive with block size of 4 KB. The size of search key is 12 bytes and the size of tree/disk pointer is 8 bytes. Assume that the database has one million records. Also assume that no node of the B+ tree and no records are present initially in main memory. Consider that each record fits into one disk block. The minimum number of disk accesses required to retrieve any record in the database is ______.

A library relational database system uses the following schema

USERS (User#, UserName, HomeTown)
BOOKS (Book#, BookTitle, AuthorName)
ISSUED (Book#, User#, Date) 

Explain in one English sentence, what each of the following relational algebra queries is designed to determine

(a) σ User #=6 (11 User #, Book Title ((USERS ISSUED) BOOKS))
(b) σ Author Name (BOOKS (σ Home Town) = Delhi (USERS ISSUED))) 

For a database relation R(a,b,c,d), where the domains a, b, c, d include only atomic values, only the following functional dependencies and those that can be inferred from them hold:

   a → c 
   b → d  

This relation is

Let R(a,b,c) and S(d,e,f) be two relations in which d is the foreign key of S that refers to the primary key of R. Consider the following four operations R and S

   (a) Insert into R            (b) Insert into S 
   (c) Delete from R            (d) Delete from S    

Which of the following can cause violation of the referential integrity constraint above?

Given two union compatible relations R₁(A,B) and R₂(C,D), what is the result of the operation R₁A = CAB = DR₂?

Which normal form is considered adequate for normal relational database design?

There are 5 records in a database.

There is an index file associated with this and it contain the values 1, 3, 2, 5 and 4. Which one of the fields is the index built form?

Which of the following query transformations (i.e. replacing the l.h.s. expression by the r.h.s. expression) is incorrect? R₁ and R₂ are relations, C₁, C₂ are selection conditions and A₁, A₂ are attributes of R₁?

(a) Suppose we have a database consisting of the following three relations.
FREQUENTS(student, parlor) giving the parlors each student visits.
SERVES(parlor, ice-cream) indicating what kind of ice-creams each parlor serves.
LIKES(student, ice-cream) indicating what ice-creams each parlor serves.
(Assuming that each student likes at least one ice-cream and frequents at least one parlor)
Express the following in SQL:
Print the students that frequent at least one parlor that serves some ice-cream that they like.

(b) In a computer system where the ‘best-fit’ algorithm is used for allocating ‘jobs’ to ‘memory partitions’, the following situation was encountered:

When will the 20K job complete? Note – This question was subjective type.

(a) Four jobs are waiting to be run. Their expected run times are 6, 3, 5 and x. In what order should they be run to minimize the average response time?

(b) Write a concurrent program using par begin – par end to represent the precedence graph shown below.

Consider the following database relations containing the attributes

Book_id 
Subject_Category_of_book
Name_of_Author
Nationality_of_Author 
with Book_id as the Primary Key. 

(a) What is the highest normal form satisfied by this relation?

(b) Suppose the attributes Book_title and Author_address are added to the relation, and the primary key is changed to (Name_of_Author, Book_Title), what will be the highest normal form satisfied by the relation?

Consider the following relational database schemes:

  COURSES(Cno, name)
  PRE-REQ(Cno, pre_Cno)
  COMPLETED(student_no, Cno) 

COURSES give the number and the name of all the available courses.
PRE-REQ gives the information about which course are pre-requisites for a given course.
COMPLETED indicates what courses have been completed by students.

Express the following using relational algebra:
List all the courses for which a student with student_no 2310 has completed all the pre-requisites.

Consider the join of a relation R with a relation S. If R has m tuples and S has n tuples then the maximum and minimum sizes of the join respectively are

The relational algebra expression equivalent to the following tuple calculus expression:

Let R = (A, B, C, D, E, F) be a relation scheme with the following dependencies: C→F, E→A, EC→D, A→B. Which of the following is a key of R?

Which of the following is correct?

Consider the schema R = (S T U V) and the dependencies S → T, T → U, U → V and V → S. Let R = (R1 and R2) be a decomposition such that R1 ∩ R2 ≠ ∅ . The decomposition is

Consider the circuit shown below. In a certain steady state, the line Y is at ‘1’. What are the possible values of A, B and C in this state?

Which of the following sets of component(s) is/are sufficient to implement any arbitrary Boolean function?

Which of the following is/are correct?

Consider a B-tree with degree m, that is, the number of children, c, of any internal node (except the root) is such that m ≤ c ≤ 2m-1. Derive the maximum and minimum number of records in the leaf nodes for such a B-tree with height h, h≥1. (Assume that the root of a tree is at height 0.)

Consider the set of relations

EMP(Employee-no, Dept-no, Employee-name, Salary)
DEPT(Dept-no, Dept-name, Location) 

Write an SQL query to:
(a) Find all employee names who work in departments located at “Calcutta” and whose salary is greater than Rs. 50,000.
(b) Calculate, for each department number, the number of employees with a salary greater than Rs. 100,000.

B⁺-trees are preferred to binary trees in databases because

Given the relations

   employee (name, salary, deptno) and
   department (deptno, deptname, address)  

Which of the following queries cannot be expressed using the basic relational algebra operations (σ, π, ×, ⋈, ∪, ∩, -)?

Given the following relation instance.

          x  y  z
          1  4  2
          1  5  3
          1  6  3
          3  2  2  

Which of the following functional dependencies are satisfied by the instance?

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

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?

(a) Suppose you are given an empty B⁺-tree where each node (leaf and internal) can store up to 5 key values. Suppose values 1,2,….. 10 are inserted, in order, into the tree, Show the tree pictorially
(i) After 6 insertions, and
(ii) After all 10 insertions
Do NOT show intermediate stages.

(b) Suppose instead of splitting a node when it is full, we try to move a value to the left sibling. If there is no left sibling, or the left sibling is full, we split the node. Show the tree after values, 1, 2,….., 9 have been inserted. Assume, as in (a) that each node can hold up to 5 keys.

(c) In general, suppose a B⁺-tree node can hold a maximum of m keys, and you insert a long sequence of keys in increasing order. Then what approximately is the average number of keys in each leaf level node.
(i) In the normal case, and
(ii) With the insertion as in (b).

Consider a bank database with only one relation
transaction (transno, acctno, date, amount)
The amount attribute value is positive for deposits and negative for withdrawals.

(a) Define an SQL view TP containing the information.
(acctno, T1.date, T2.amount)
for every pair of transactions T1, T2 such that T1 and T2 are transaction on the same account and the date of T2 is ≤ the date of T1.

(b) Using only the above view TP, write a query to find for each account the minimum balance it ever reached (not including the 0 balance when the account is created). Assume there is at most one transaction per day on each account, and each account has had atleast one transaction since it was created. To simply your query, break it up into 2 steps by defining an intermediate view V.

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

With regard to the expressive power of the formal relational query languages, which of the following statements is true?

A B⁺– tree index is to be built on the Name attribute of the relation STUDENT. Assume that all student names are of length 8 bytes, disk blocks are of size 512 bytes, and index pointers are of size 4 bytes. Given this scenario, what would be the best choice of the degree (i.e. the number of pointers per node) of the B⁺-tree?

Relation R is decomposed using a set of functional dependencies, F, and relation S is decomposed using another set of functional dependencies, G. One decomposition is definitely BCNF, the other is definitely 3NF, but it is not known which is which. To make a quaranteed identification, which one of the following tests should be used on the decompositions? (Assume that the closures of F and G are available).