Database Systems

Database Systems: Components and Concepts

• A database is an organised collection of related data. It facilitates data management, data search, and data storage.
• A Database Management System (DBMS) is a software application used to access, manage, store, and retrieve data from databases.
• Data in a database is structured into tables, each representing a different aspect of information e.g., students, courses, books etc.
• Tables are further divided into rows (records) and columns (fields). Each record represents a specific item in the table, while each field represents a property or attribute of the item.
• Primary keys are used to uniquely identify each record in a table. No two records can have the same primary key within the same table.
• Foreign keys are used to establish a link between two tables. They allow databases to enforce referential integrity by ensuring the data in each field matches the data in a column of another table.

Relational Database Management Systems (RDBMS)

• RDBMS uses a structured query language (SQL) for defining and manipulating the data. SQL includes DDL (Data Definition Language) for creating and modifying tables, and DML (Data Manipulation Language) for inserting, updating, and deleting data.
• RDBMS employs a relational model where data is organised into one or more tables.
• Normalization is a database design technique used in RDBMS to minimise data redundancy and avoid data anomalies.
• Entity Relationship Diagram (ERD) is a graphical representation of an organisation’s data storage requirements. It identifies the entities, relationships, and attributes that need to be stored in the database.

Database Security

• Data backup is the process of creating duplicate copies of databases that can be restored in case of a system failure or data loss.
• Data recovery is the process of restoring data from the backup after a data loss event.
• Database access controls prevent unauthorized access to databases, assuring data integrity, confidentiality, and availability.
• Encryption is a process of converting data into a form that’s hard to read without a decryption key or password. It’s used to protect sensitive information in databases from unauthorized access or alteration.

Data Warehouse and Data Mining

• A data warehouse is a large, centralised database that stores historical and cumulative data from multiple sources. It’s used for reporting and data analysis.
• Data mining is the process of discovering patterns, relationships and trends in large datasets to predict future behaviours and guide decision making.

Database Technologies and Applications

• Cloud databases are hosted on a platform hosted by a cloud service provider, enabling organisations to store, manage, and retrieve data more efficiently.
• NoSQL databases are used for handling Big Data. They’re capable of handling data that doesn’t fit into the tabular structure of traditional relational databases.
• Distributed databases are databases in which storage devices are not all attached to a common processor but spread across multiple locations. It increases reliability, availability, and the speed of data access.