Data Structures (CS113) Level 3, First Term

Study Notes

Data is a collection of facts and figures that needs to be stored in a device or software that is safer.
Charles Bachman developed the Integrated Data Store (IDS) based on the network data model, for which he received the Turing Award.
IBM developed the Integrated Management Systems, a standard database system that is still used today, based on the hierarchical database model.

Edgar Codd developed the relational database model, considered the standardized database model.
IBM developed Structured Query Language (SQL) as part of the R project, which was declared a standard language for queries by ISO and ANSI.

A database management system is a software package for creating and managing databases.
There are two basic forms of databases: single-file or flat file database and multi-file relational or structured database.
Flat file databases store data in a plain text file, while relational databases contain multiple tables of data with rows and columns that relate to each other.

There are four types of relationships in relational database design:
- One-to-one: one table record relates to another record in another table.
- One-to-many: one table record relates to multiple records in another table.
- Many-to-one: more than one table record relates to another table record.
- Many-to-many: multiple records relate to more than one record in another table.

A relational database management system is one of four common types of systems used to manage business data.
A DBMS serves as an interface between the database and its end users or programs, allowing users to retrieve, update, and manage how the information is organized and optimized.

Uses a digital repository established on a server to store and manage information.
Provides a clear and logical view of the process that manipulates data.
Contains automatic backup and recovery procedures.
Has ACID properties which maintain data in a healthy state in case of failure.
Reduces the complex relationship between data.
Supports manipulation and processing of data.
Provides security of data.
Can view the database from different viewpoints according to the requirements of the user.

Controls database redundancy by storing all the data in one single database file.
Allows authorized users to share the data among multiple users.
Is easily maintainable due to the centralized nature of the database system.
Reduces development time and maintenance needs.
Provides backup and recovery subsystems which create automatic backup of data and restores the data if required.
Provides multiple user interfaces like graphical user interfaces, application program interfaces.

Requires high-speed data processor and large memory size to run DBMS software.
Occupies a large space of disks and large memory to run them efficiently.
Creates additional complexity and requirements.
Failure has a higher impact on the database, which can result in data loss if the database is damaged due to electric failure or database corruption.