DB

Question 1

Types of DBMS Models

Answer 1

Hierarchical DB
Network
ER Model
Relational DB

Question 2

DB Model

Answer 2

A database model is a type of data model that determines the logical structure of a database. It fundamentally determines in which manner data can be stored, organized and manipulated.

Question 3

Drop vs Truncate syntax

Answer 3

Syntax» Drop: delete an entire table or db

Truncate: Delete specific data within the db

Question 4

Database Transaction

Answer 4

A Database Transaction is a logical unit of processing in a DBMS which entails one or more database access operation. a database transaction is a single unit of all the dynamics involved in one or more database operationsIn a nutshell, database transactions represent real- world events of any enterprise.

Question 5

ACID Properties of a DB

Answer 5

Atomicity
Consistency
Isolation
Durability

Question 6

Define ACID properties of a DB

Answer 6

ACID Properties are used for maintaining the integrity of database during transaction processing. ACID in DBMS stands for Atomicity, Consistency, Isolation, and Durability.

Question 7

External Model of a DB

Answer 7

The external model is the end user’s view of the data. Typically a database is an enterprise system that serves the needs of multiple departments. However, one department is not interested in seeing other departments’ data (e.g., the human resources (HR) department does not care to view the sales department’s data).

Question 8

Conceptual design

Answer 8

Conceptual design is the first stage in the database design process. The goal at this stage is to
design a database that is independent of database software and physical details. The output of this process is a conceptual data model that describes the main data entities, attributes, relationships, and constraints of a given problem domain.
Keep in mind the following minimal data rule:
“All that is needed is there, and all that is there is needed”.

Question 9

Schema

Answer 9

schema is the skeleton structure that represents the logical view of the entire database. The blueprint for how data is organized and stored within the database, specifying the tables, fields, data types, constraints, and relationships between tables.

Question 10

reasons for database abstraction level

Answer 10

1. Data Independence
2. Application Portability
3. Security
4. Access Control
5. Query Optimization
6. High Availability
7. Scalability
8. Cross-Platform Compatibility

Question 11

Importance of DB Transaction Log

Answer 11

Security
High Availability
Archive
PIT recovery
Rollback support

Question 12

SQL Statements used in DB

Answer 12

Commit
Rollback

Question 14

Levels of transaction isolation

Answer 14

Non committed reads
Committed reads
Repeatable reads
Serialized

Question 15

Main components of a db

Answer 15

Software
Hardware
Data
Procedures
Data access language