DBMS Basics

Question 1

What is data

Answer 1

Facts about and entity that can be recorded or stored

Question 2

What is information

Answer 2

Processed,meaningful and usable data

Question 3

What is information

Answer 3

Processed,meaningful and usable data

Question 4

What is Database

Answer 4

Collection of logically related data

Question 5

Define Management

Answer 5

Manipulation,Searching and Security of Data

Question 6

Define Database Management System

Answer 6

Set of programs or software used to define,manipulate, retrieve and manage data in a database.

Question 7

DB+DBMS=

Answer 7

DB + DBMS = DBS (Database System)

Question 8

Whats File processing System

Answer 8

• A file processing system is a software that stores and manage files in computer
  hard disk.
• It allows access to single files or tables at a time.
• Data is directly stored in set of files.
• It contains flat files that have no relation to other files.
• File system consists of different files which are grouped into directories.
  The directories further contain other folders and files.
• E.g. NTFS (New Technology File System), EXT (Extended File System)

Question 9

Disadvantages file-processing system are!?

Answer 9

• Data redundancy and inconsistency
• Difficulty in accessing data
• Data isolation
• Integrity problems

Question 10

Whats Data redundancy and inconsistency

Answer 10

• Redundancy occurs when same piece of the data is held in two or more separate places.
• Inconsistency occurs when same data is kept in different format or have different values at two or more places.

Question 11

Whats Difficulty in accessing data

Answer 11

It does not allow needed data to be retrieved in a convenient and efficient manner

Question 12

Whats Data isolation

Answer 12

Data is scattered in various files, and files may be in different formats.

Question 13

Whats Integrity problems

Answer 13

The data values stored in the database must satisfy certain types of constraints.

Question 14

What are the Characteristics of the Database Approach

Answer 14

• In the database approach, a single repository maintains data.
• It should be accessed by various users repeatedly through queries, transactions,
  and application programs.
• The main characteristics of the database approach are:
• Self-describing nature of a database system
• Insulation between programs and data, and data abstraction
• Support of multiple views of the data
• Sharing of data and multiuser transaction processing

Question 15

What is Meta Data

Answer 15

The structure of each file, the type and storage format of each data item, and various constraints on the data.
This information is called meta-data.

Question 16

Whats DBMS Architecture

Answer 16

• The DBMS design depends upon its architecture. The basic client/server architecture is used to
  deal with a large number of PCs, web servers, database servers and other components that are
  connected with networks.
• This architecture consists of many PCs and a workstation which are connected via the network.
• DBMS architecture depends upon how users are connected to the database to get their
  request done.

Question 17

Types of DBMS Architectures are

Answer 17

1-Tier Architecture
2-Tier Architecture
3-Tier Architecture

Question 18

Whats 1-Tier Architecture ?!

Answer 18

• The database is directly available to the user.
• Any changes done here will directly be done on the database itself. It doesn’t provide a handy tool for
  end users.
• The 1-Tier architecture is used for development of the local application, where programmers can
  directly communicate with the database for the quick response.

Question 19

Whats 2-Tier Architecture?!

Answer 19

The 2-Tier architecture is same as basic client-server. In the two-tier architecture, applications on the
client end can directly communicate with the database at the server side. For this interaction, API’s
like: ODBC, JDBC are used.
* The user interfaces and application programs are run on the client-side.
* To communicate with the DBMS, client-side application
establishes a connection with the server side.

Question 20

Whats 3-Tier Architecture?

Answer 20

• The 3-Tier architecture contains another layer between the client and server. Here, client can’t directly communicate with the server.
• The application on the client-end interacts with an application server which further communicates with the database system.
• End user has no idea about the existence of the database beyond the application server. The database also has no idea about any other user beyond the application.
• The 3-Tier architecture is used in case of large web application.

Question 21

Whats database schema!?

Answer 21

The description of a database is called the database schema.
* Includes descriptions of the database structure, data types, and the constraints
on the database.
* It is specified during database design and is not expected to change frequently.
* Each object in the schema—such as STUDENT or COURSE— called a schema
construct.

Question 22

Whats Database state/snapshot

Answer 22

The data in the database at a particular moment in time is called a
database state or snapshot
* It changes every time we add new data in database.
* It is also called the current set of occurrences or instances in
the database.

Question 23

Disadvantage of file processing system:

Answer 23

• Atomicity problems
• It is essential in database that either complete query to be executed, or none, which means
  either all the operations in a transaction executes or none.
• Concurrent-access anomalies
• For faster response, many systems allow multiple users to update the data simultaneously.

Question 24

Whats three Schema Architecture

Answer 24

• Internal schema describes the physical storage structure and access paths.
• Typically uses a physical data model.
• Conceptual schema describes the structure and constraints for the whole database for different users.
• The conceptual schema hides the details of physical storage structures and focuses on describing entities, data types, relationships, constraints, etc.
• Uses a conceptual or an implementation data model.* External schemas (view schemas) describes the part of the database that a particular user is interested in and
  hides the remaining database from that user group.
• The view schema describes the end user interaction with database systems.
• Usually uses the same data model as the conceptual schema.

Question 25

Whats Data abstraction

Answer 25

To ease the user interaction with database, the developers hide internal irrelevant
details from the users and provides abstract view of data to users. This process of
hiding irrelevant details from user is called Data Abstraction.

Question 25

Whats Data Independence

Answer 25

Data independance means if we enter new data or update,rest of the data should not been displaced or disturbed

Question 26

What is Cardinality Ratio

Answer 26

Cardinality Ratio: It defines minimum and maximum entity occurrences that participating in
a relationship.

Question 27

Whats Weak entity set

Answer 27

Weak Entity Set
} Entity types that do not have any key attribute and can not be identified independently are called weak entity.
} The existence of a weak entity set depends on the existence of a strong entity set
} Entities belonging to a weak entity set are identified by being related to specific entities from another entity set in combination with one of their attribute values.