Unit 3 TYPES OF DATABASES AND FILE SYSTEMS”

Number of Users and Location

What are the 2 TYPES OF DATABASES AND FILE SYSTEMS

Single-user database

• Database that supports one user at a time

• For personal devices and small - scale application (PC, Phone Apps, Single player offline games)

Advantages of Single User Database

• Easy to use

• No need for complex network setup

• Fast access for 1 person

• Low maintenance

Disadvantages of Single User Database

• Cannot support multiple users

• Limited scalability

• Not suitable for businesses that need data sharing

Multiuser database

• Allows multiple users to access data simultaneously

• Managed by a DBMS (Database Management System)

• Used by businesses, organizations, and online systems (E commerce, Airline reservation, School database, Online Games)

Advantages of Multi User Database

• Data sharing among multiple users

• Better scalability for large systems

• Increases productivity in organizations

Disadvantages of Multi User Database

• More complex to set up and maintain

• Requires strong security and backup systems

• Higher cost (Hardware + Software)

• Performance may drop if too many users access at once

Centralized Database

• Database is maintained in a central location (Centralized DBMS)

• All users connect one central server

• Data is uploaded and managed in one central system

• Users access through a network (LAN, WLAN, or Internet

• Examples : Government Database, University Database, Banking Systems

Advantages of Centralized Database

• Data consistency (Only one copy of data)

• Easier to backup

• Centralized control improves reliability

• Simple to manage and update

Disadvantages of Centralized Database

• Single point of Failure

• High network dependency

• Can become slow with too many users

• Expensive to maintain large central servers

Decentralized Database

• Data is stored across multiple independent locations

• Each location has its own database and control, but may share information with others

• No single point of control

• Examples: Transferring records from Hospitals

Advantages of Decentralized Database

• No single point of failure

• Improved reliability and fault tolerance

• Local control over data

• Scales well across multiple location

Disadvantages of Decentralized Database

• Harder to maintain data consistency

• More complex to manage and synchronize

• May require stronger security protocols

• Higher setup and maintenance cost

Distributed Database

• It is when the data is stored on multiple computers/servers that are connected by a network, (works all together as if they’re one single database)

• Eg: A bank branch in Manila stores data about its customers. The branch in Cebu does the same. Both are part of a single database system. So if you withdraw money in Cebu, you can still check your balance in Manila.

ADVANTAGES of Distributed Database

• If one server fails, others will still work

• Faster access because data is closer to users.

• Can handle more users and bigger data

DISADVANTAGES of Distributed Database

• Harder to manage

• Data might not always match (Sync problems)

• More expensive as it needs more servers

Structured Data

 Data that is organized in rows and columns (Ex. Student Records, Bank transactions)

Unstructured Data

Is a data that doesn’t fit neatly into tables. It has no fixed format (Ex. Images, Videos, Audio files).

Semi-Structured

is a mix of both, not as rigid as structured yet still has some organization(like tags or keys). It is a data that is partly organized but not as strict as a table. (Ex. Emails, Student Evaluation)

Database Design

• Is the process of planning how data will be stored, organized, and connected in a database. The design of the database varies on the client’s needs

Manual File System

• Is the old way of storing and organizing data before computers and databases existed.

• Using physical files like paper, file folders and filing cabinets to keep records

DDOES NOT USE D

transaction

a unit of work in a database (such as transferring

money, placing an order, or enrolling a student).

ACID Properties

guarantee that database transactions are

processed reliably.

Consistency

Define what ACID Property that is shown in the scenario:
each studentID must be unique, otherwise DBMS wont allow you to proceed

Isolation

• Even if many people are using the database at the same time, each transaction acts as if one is only happening

• No mix up between transactions

Isolation

Define what ACID Property that is shown in the scenario:
 If two people deposit money into the same account at the same time, each transaction should be recorded correctly, not overwrite the other.

Durability

• Once a transaction is finished and saved, it will never be lost, even if the system crashes right after

• STAYS PERMANENT

Durability

Define what ACID Property that is shown in the scenario:
Once payment is confirmed, the order record should remain, even if the website crashes right after.

Atomicity

• Transaction is treated as one complete unit

• All steps should be done or, nothing will happen.

• (All or Nothing Rule

Atomicity

Define what ACID Property that is shown in the scenario:
Cash dispensed and balance updated must both happen, or nothing happens.

Consistency

• Make sure the database follows all the rules before and after transaction

• If rules are broken, transaction will fail. BUT will go back to it’s LAST safe state