Overview of databases

Content summary

This lesson introduces the key concepts of: - Databases - Database Management Systems - Database Systems

Database

Concept

A database is a collection of data that is organized and stored in a way that makes searching, processing, and managing data more efficient.

Databases are commonly used to handle large amounts of data for individuals and organizations across many different fields.

Properties

1. Structured

   Structured means the data is organized and stored in a specific format.

   Example:
   Data can be arranged in tables, where both rows and columns follow predefined rules.

2. Consistency

   Consistency is part of accuracy and reliability. Specifically, during updates, data must be kept free of errors, contradictions, or conflicts.

   Example:
   When student Tèo transfers from class 11A to 11D, the data in both classes — and all related records — must be updated correctly so there are no inconsistencies, such as:

   • Tèo appearing in both class lists.
   • Competition results still being counted for 11A when they should be for 11D.

3. Integrity

   Integrity means the data is correct, reliable, and consistent. Before being saved, data must follow rules and constraints to ensure it is valid and free from "garbage" (invalid) data.

   Example:
   Test scores must be between 0 and 10. If a user enters 11 and the database allows it, integrity is violated.

4. Security

   Security refers to controlling access to the database to prevent unauthorized access tampering or invalid changes.

   Example:
   A teacher should not be allowed to edit grades for classes they do not teach.

Database management system

Concept

A database management system, abbreviated as DBMS, is software that helps users store, manage, process, and query databases.

Examples:
Some popular DBMSs in use today include:

• Oracle
• MySQL
• Microsoft SQL Server
• PostgreSQL
• MongoDB

Functions

The DBMS acts as an intermediary between application software and the database, providing efficient and secure ways to interact with and control data. Its main functions are:

1. Data storage

   Manages physical data storage, including:

   • How data is stored on disk
   • File organization

   • Indexing (1)

     1. Indexing is the process of creating special data structures called indexes to speed up data retrieval.

        With an index, searching becomes much faster because the system can locate the needed data without scanning the entire table.

2. Data retrieval

   Allows data to be searched using query languages, such as SQL.

3. Data processing

   Enables adding, updating, and deleting data while maintaining consistency and integrity of the database.

   Additionally, a DBMS provides other important features, such as:

   • Data security
   • Data integrity enforcement
   • Concurrent access control
   • Transaction management
   • Backup and recovery
   • Query optimization
   • Statistics, analysis, and reporting
   • Multi-user support
   • and more...

Database system

A database system consists of:

• The database
• The database management system
• Application software

Components of a database system

Even though the DBMS exists, application software is still developed to make it easier and more convenient for users to interact with the database.

Summary mindmap

Some English words

Vietnamese	Tiếng Anh
cơ sở dữ liệu	database
hệ cơ sở dữ liệu	database system
hệ quản trị cơ sở dữ liệu	database management system (DBMS)
phần mềm ứng dụng	application software

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