A database management system (DBMS) is software designed to define, manipulate, retrieve, and manage data in a database. The primary goal of a DBMS is to provide convenient and efficient ways to store and retrieve database information. It manages data by defining the structure for storing information and providing mechanisms for manipulating that information.

2. 1Q.What do you mean by DBMS? What is the main goal of it.
A database management system (DBMS) is a software package
designed to define, manipulate, retrieve and manage data in a
database. A DBMS generally manipulates the data itself, the data
format, field names, record structure and file structure. It also defines
rules to validate and manipulate this data.
Primary goal of database management system is to provide a way to
store and retrieve database information that is convenient and efficient.
Management of data involves both defining structure for storage of
information and providing mechanism for manipulation of information.

3. Q. Explainthe purpose DDL and DML
DDL stands for Data Definition Language. It is used to define database structure or pattern.
• It is used to create schema, tables, indexes, constraints, etc. in the database.
• Using the DDL statements, you can create the skeleton of the database.
• Data definition language is used to store the information of metadata like the number of
tables and schemas, their names, indexes, columns in each table, constraints, etc
DML stands for Data Manipulation Language. It is used for accessing and manipulating data
in a database. It handles user requests.

4. Q. Describe the function of DBA.
SQL consists of three components:
• Data Definition Language (DDL)
• Data Manipulation Language (DML)
• Data Control Language (DCL)
The Data Definition Language (DDL). This component of the SQL language is used to create and
modify tables and other objects in the database. For tables there are three main commands:
• CREATE TABLE tablename to create a table in the database
DROP TABLE tablename to remove a table from the database
ALTER TABLE tablename to add or remove columns from a table in the database
The Data Manipulation Language (DML) component of the SQL language is used to manipulate
data within a table. There are four main commands:
• SELECT to select rows of data from a table
INSERT to insert rows of data into a table
UPDATE to change rows of data in a table
DELETE to remove rows of data from a table
The Data Control Language (DCL) This component of the SQL language is used to create
privileges to allow users access to, and manipulation of, the database. There are two main commands:
• GRANT to grant a privilege to a user
REVOKE to revoke (remove) a privilege from a user

5. 2Q. What do you mean by entity set and relationship set.
Ans. An entity set is a set of entities of the same type (e.g., all persons having an account
at a bank). Entity sets need not be disjoint. For example, the entity set employee (all
employees of a bank) and the entity set customer (all customers of the bank) may have
members in common.
Types of Entity Sets-
• Strong entity set
• Weak entity set
A relationship set is a set of relationships of the same type. ... For example, consider the
two entity sets customer and account. (Fig. 2.1 in the text). We define the relationship
CustAcct to denote the association between customers and their accounts.
Types of Relationship Sets-
• Unary relationship set
• Binary relationship set
• Ternary relationship set
• N-ary relationship se

6. Q. Explain different types of attributes and there representation in ER diagram
An attribute describes the property of an entity. An attribute is represented as Oval in an ER diagram. There are four types of attributes:
• 1. Key attribute
2. Composite attribute
3. Multivalued attribute
4. Derived attribute
1. Key attribute: A key attribute can uniquely identify an entity from an entity set. For example, student roll number can uniquely identify a
student from a set of students. Key attribute is represented by oval same as other attributes however the text of key attribute is underlined.
2. COMPOSITE ATTRIBUTE. An attribute that can be divided into smaller independent attribute is known as composite attribute.
3. Multivalued attribute: An attribute that can hold multiple values is known as multivalued attribute. It is represented with double ovals in an
ER Diagram. For example – A person can have more than one phone numbers so the phone number attribute is multivalued.
4.DERIVED ATTRIBUTE. An attribute that can be derived from another attribute is known as derived attribute.

7. Q. Define weak entity set & strong entity set? How they showed in ER diagram.
• Strong Entity: Strong entity is not dependent of any other entity in schema.
Strong entity always has primary key. Strong entity is represented by single
rectangle. Two strong entity’s relationship is represented by single diamond.
Various strong entities together makes the strong entity set.
• Weak Entity: Weak entity is depend on strong entity to ensure the existance of
weak entity. Like strong entity weak entity does not have any primary key, It has
partial discriminator key. Weak entity is represented by double rectangle.
The relation between one strong and one weak entity is represented by double
diamond.

8. 3Q. What is quarry language? Classify them.
• Definition : Query language (QL) refers to any computer programming language that requests and
retrieves data from database and information systems by sending queries. It works on user
entered structured and formal programming command based queries to find and extract data
from host databases.
Query language may also be termed database query language.
Query language is primarily created for creating, accessing and modifying data in and out from a
database management system (DBMS). Typically, QL requires users to input a structured command
that is similar and close to the English language querying construct.
• For example, the SQL query: SELECT * FROM
Classify
• Thematic query:
Selection of all objects which achieve the required conditions (attributes). E.g.: "Select all spruce
trees."
• Geometric query:
Selection of all objects which achieve the required spatial conditions. E.g.: "Select all the houses
that are located less than 250 m away from the river".
• Topological query:
Selection of all objects which achieve the required conditions regarding the spatial relations
between the objects. For example: "Select all the buildings that are lying in zone 1".

9. Q. Explain fundamental operations of relational algebra
Relational algebra is a widely used procedural query language. It collects instances
of relations as input and gives occurrences of relations as output. It uses various
operation to perform this action.
Relational algebra operations are performed recursively on a relation. The output
of these operations is a new relation, which might be formed from one or more
input relations.
Basic Relational Algebra Operations:
1. Unary Relational Operations
2. Relational Algebra Operations From Set Theory
3. Binary Relational Operations
4. SELECT (σ)
5. Projection(π)
6. Union operation (υ)
7. Intersection
8. Cartesian product(X)
9. Join Operations

10. Q. Explain Cartesian product operations of relational algebra
The Cartesian Product is also an operator which works on two sets. It is
sometimes called the CROSS PRODUCT or CROSS JOIN. It combines the
tuples of one relation with all the tuples of the other relation.

11. 4Q. Discuss Several part of SQL language.
SQL consists of three components:
• Data Definition Language (DDL)
• Data Manipulation Language (DML)
• Data Control Language (DCL)
The Data Definition Language (DDL). This component of the SQL language is used to create and
modify tables and other objects in the database. For tables there are three main commands:
• CREATE TABLE tablename to create a table in the database
DROP TABLE tablename to remove a table from the database
ALTER TABLE tablename to add or remove columns from a table in the database
The Data Manipulation Language (DML) component of the SQL language is used to manipulate
data within a table. There are four main commands:
• SELECT to select rows of data from a table
INSERT to insert rows of data into a table
UPDATE to change rows of data in a table
DELETE to remove rows of data from a table
The Data Control Language (DCL) This component of the SQL language is used to create
privileges to allow users access to, and manipulation of, the database. There are two main commands:
• GRANT to grant a privilege to a user
REVOKE to revoke (remove) a privilege from a user

12. Q. Explain the basic structure of SQL.
A relational database is a collection of tables. Each table has its own unique name.
The basic structure of an SQL expression consists of three clauses:
• The select clause which corresponds to the projection operation. It is
the list of attributes that will appear in the resulting table.
• The from clause which corresponds to the Cartesian-product
operation. It is the list of tables that will be joined in the resulting
table.
• The where clause which corresponds to the selection operation. It is
the expression that controls the which rows appear in the resulting
table.
Example : select dept_name
from instructor;
where dept_name = ’Comp. Sci.’ and salary > 70000;

13. 7Q. Define transaction?
Q. Discuss ACID properties.
A transaction is a single logical unit of work which accesses and possibly modifies
the contents of a database. Transactions access data using read and write
operations. In order to maintain consistency in a database, before and after the
transaction, certain properties are followed. These are called ACID properties.

14. Q. Explain deadlock & deadlock handling procedure
Deadlock : Deadlock is a state of a database system having two or more transactions,
when each transaction is waiting for a data item that is being locked by some other
transaction. A deadlock can be indicated by a cycle in the wait-for-graph. This is a
directed graph in which the vertices denote transactions and the edges denote waits
for data items.
• Example:
•  For example, in the following wait-for-graph, transaction T1 is waiting for data item X
which is locked by T3. T3 is waiting for Y which is locked by T2 and T2 is waiting for Z which is
locked by T1. Hence, a waiting cycle is formed, and none of the transactions can proceed
executing.

15. Cont.
•DEADLOCK HANDLING
• When a deadlock occurs, different operating systems
respond to them in different non- standard manners.
• The Major approaches are as follows
1. IGNORING DEADLOCK
2. DETECTION

16. 6Q. What do you mean by domain constraints? Explain.
Q. Define referential integrity? Show how a foreign key declare
in SQL.
• Domain constraints can be defined as the definition of a valid set of
values for an attribute. The data type of domain includes string,
character, integer, time, date, currency, etc. The value of the attribute
must be available in the corresponding domain.
• Referential integrity (RI) is a relational database concept, which
states that table relationships must always be consistent. In other
words, any foreign key field must agree with the primary key that is
referenced by the foreign key. Thus, any primary key field changes
must be applied to all foreign keys, or not at all. The same restriction
also applies to foreign keys in that any updates (but not necessarily
deletions) must be propagated to the primary parent key.

17. Cont.
• SQL FOREIGN KEY on CREATE TABLE
The following SQL creates a FOREIGN KEY on the "PersonID" column
when the "Orders" table is created:
CREATE TABLE Orders (
OrderID int NOT NULL,
OrderNumber int NOT NULL,
PersonID int,
PRIMARY KEY (OrderID),
FOREIGN KEY (PersonID) REFERENCES Persons(PersonID)
);

18. Q. Explain database trigger?
A database trigger is special stored procedure that is run when specific actions occur
within a database. Most triggers are defined to run when changes are made to a table's
data. Triggers can be defined to run instead of or after DML actions such as INSERT,
UPDATE, and DELETE.
Example–
Suppose, we are adding a tupple to the ‘Donors’ table that is some person has donated
blood. So, we can design a trigger that will automatically add the value of donated blood to
the ‘Blood_record’ table.
Types of Triggers –We can define 6 types of triggers for each table:
• AFTER INSERT activated after data is inserted into the table.
• AFTER UPDATE: activated after data in the table is modified.
• AFTER DELETE: activated after data is deleted/removed from the table.
• BEFORE INSERT: activated before data is inserted into the table.
• BEFORE UPDATE: activated before data in the table is modified.
• BEFORE DELETE: activated before data is deleted/removed from the table.

19. 7Q. What is the difference between centralized and client server system.
Centralized System Architecture:
• Centralized means the data is in one place.
• Centralized database - that is have one large computer to which you
connect a large number of terminals. Everyone is working directly on
the machine that holds the database.
Client-server Architecture:
• Client server just means the clients are in a different place than the
data. It simply means the database is considered one unit managed
by one DBMS in one location and to which clients connect.
• Client/Server DB system relies [traditionally] on a single database-
server, which passes information to a client machine, where some of
the data processing is done

20. Q. Discuss different types of database architecture
DBMS Architecture: 1-Tier, 2-Tier & 3-Tier
1 tier Architecture :The simplest of Database Architecture are 1 tier where the Client, Server, and Database all reside
on the same machine. Anytime you install a DB in your system and access it to practise SQL queries it is 1 tier
architecture. But such architecture is rarely used in production.
2-tier Architecture
• A two-tier architecture is a database architecture where
• Presentation layer runs on a client (PC, Mobile, Tablet, etc)
• Data is stored on a Server.
• An application interface which is called ODBC (Open Database Connectivity) an API which allows the client-side
program to call the DBMS. Today most of the DBMS offers ODBC drivers for their DBMS. 2 tier architecture provides
added security to the DBMS as it is not exposed to the end user directly.
3-tier Architecture : 3-tier schema is an extension of the 2-tier architecture. 3-tier architecture has following
layers
1.Presentation layer (your PC, Tablet, Mobile, etc.)
2.Application layer (server)
3.Database Server
Goal
•Proposed to support DBMS characteristics
•Program-data independence
•Support of multiple views of the data

21. Q. Discuss different types of failure in database system.
Failure Classification
• Transaction failure
• System crash
• Disk failure
1. Transaction failure : The transaction failure occurs when it fails to execute or when it reaches a
point from where it can't go any further. If a few transaction or process is hurt, then this is
called as transaction failure. Reasons for a transaction failure could be –(a) Logical errors (b)
Syntax error.
2. System Crash : System failure can occur due to power failure or other hardware or software
failure. Example: Operating system error.
3. Disk Failure
• It occurs where hard-disk drives or storage drives used to fail frequently. It was a common
problem in the early days of technology evolution.
• Disk failure occurs due to the formation of bad sectors, disk head crash, and unreachability to the
disk or any other failure, which destroy all or part of disk storage.

22. 8Q. Short note on (a) Concurrent access anomalies (b) Natural join (c) Deadlock
(d)Distributed database system
(a) Data concurrency – Concurrent access to data means more than one user is accessing the
same data at the same time. Anomalies occur when changes made by one user gets lost
because of changes made by other user. File system does not provide any procedure to stop
anomalies.
(b) A NATURAL JOIN is a JOIN operation that creates an implicit join clause for you based on the
common columns of the two tables that are being joined. Common columns are columns that
have the same name in both the tables. A NATURAL JOIN can be an INNER join, a LEFT OUTER
join, or a RIGHT OUTER join.
(c) In a database, a deadlock is an unwanted situation in which two or more transactions are
waiting indefinitely for one another to give up locks. ... As a consequence, All activity comes to
a halt and remains at a standstill forever unless the DBMS detects the deadlock and aborts one
of the transactions.
(d) A distributed database is basically a database that is not limited to one system, it is spread
over different sites, i.e, on multiple computers or over a network of computers. A distributed
database system is located on various sited that don't share physical components.