Describe three types of databases and explain the components of a DBMS.

Here are the solutions to your questions.

QUESTION SIX

a) Describe three types of databases

1. Relational Databases (RDBMS): These databases organize data into tables with rows and columns, using Structured Query Language (SQL) for data management. Relationships between tables are defined using primary and foreign keys.
2. NoSQL Databases: Designed for handling large volumes of unstructured or semi-structured data, offering flexible schemas and horizontal scalability. Examples include document databases (e.g., MongoDB), key-value stores (e.g., Redis), and graph databases.
3. Object-Oriented Databases (OODBMS): These databases store data as objects, similar to objects in object-oriented programming. They are suitable for complex data types and relationships, often used in applications requiring complex data modeling.

b) Explain the components of a DBMS
A Database Management System (DBMS) consists of several key components:

• Query Processor: This component interprets and optimizes user queries (e.g., SQL statements) to determine the most efficient way to retrieve or modify data.
• Storage Manager: Responsible for managing the storage of data on disk, including file organization, indexing, and buffer management to optimize data access.
• Transaction Manager: Ensures data integrity and consistency by controlling concurrent access to the database and providing recovery mechanisms in case of system failures.
• Data Definition Language (DDL) Processor: Handles commands that define and modify the database schema, such as creating, altering, or dropping tables and indexes.

c) Describe the logical and physical view of databases

• Logical View (Conceptual/External View): This describes how users or applications perceive the data. It focuses on the data entities, attributes, and relationships that are relevant to a specific user, abstracting away the underlying storage details. Different users can have different logical views of the same data.
• Physical View (Internal View): This describes how the data is actually stored on physical storage devices. It deals with low-level details such as file organization, indexing structures, data compression, and the physical location of data blocks on disk.

QUESTION SEVEN

Here is the CUSTOMER table:

CustomerId	CustomerNumber	LastName	FirstName	AreaCode	Address	Phone
1	1000	Smith	John	12	California	11111111
2	1001	Jackson	Smith	45	London	22222222
3	1002	Johnsen	John	32	London	33333333

a) SELECT Customer ID, Last Name, First Name FROM Customer
Output:

CustomerId	LastName	FirstName
1	Smith	John
2	Jackson	Smith
3	Johnsen	John

b) SELECT * FROM CUSTOMER ORDER BY Last Name
Output:

CustomerId	CustomerNumber	LastName	FirstName	AreaCode	Address	Phone
2	1001	Jackson	Smith	45	London	22222222
3	1002	Johnsen	John	32	London	33333333
1	1000	Smith	John	12	California	11111111

c) SELECT DISTINCT First Name FROM CUSTOMER
Output:

FirstName
John
Smith

d) SELECT * FROM CUSTOMER WHERE Last Name LIKE 'Ja%'
Output:

CustomerId	CustomerNumber	LastName	FirstName	AreaCode	Address	Phone
2	1001	Jackson	Smith	45	London	22222222

e) SELECT * FROM CUSTOMER WHERE Last Name='Smith' AND (First Name='John' OR First Name='Smith')
Output:

CustomerId	CustomerNumber	LastName	FirstName	AreaCode	Address	Phone
1	1000	Smith	John	12	California	11111111

f) SELECT TOP 1 * FROM CUSTOMER
Output:

CustomerId	CustomerNumber	LastName	FirstName	AreaCode	Address	Phone
1	1000	Smith	John	12	California	11111111