Science Knowings: JavaScript Course For Social Media

Relational Databases (MySQL, PostgreSQL)

Relational Databases: A Dive into MySQL and PostgreSQL

Welcome to the world of relational databases! In this session, we'll dive into MySQL and PostgreSQL, two widely used relational database management systems.

What are Relational Databases?

Relational databases store data in tables, where rows represent records and columns represent attributes. These tables are interconnected through relationships, forming a network of data.

Key Concepts: Tables, Rows, and Columns

TableA collection of related data organized into rows and columns.
RowA horizontal record in a table, representing a single entity.
ColumnA vertical attribute in a table, representing a specific characteristic of the entity in a row.

Relational Model and Data Integrity

The relational model ensures data integrity through relationships between tables. Foreign key constraints prevent data inconsistencies and maintain data accuracy.

Database Schemas and Normalization

Database schemas define the structure and relationships of tables. Normalization is a process of organizing data to minimize redundancy and improve data integrity.

MySQL Overview

MySQL is an open-source, widely used relational database management system known for its speed, reliability, and flexibility.

MySQL Data Types and Constraints

Data TypeDescription
INTInteger numbers
VARCHARVariable-length character strings
DATETIMEDate and time
PRIMARY KEYUnique identifier for each row
FOREIGN KEYReferences a primary key in another table

MySQL Query Language (SQL)

SQL (Structured Query Language) is used to interact with MySQL databases. It allows you to create, read, update, and delete data.

PostgreSQL Overview

PostgreSQL is another popular open-source relational database management system known for its advanced features, extensibility, and community support.

PostgreSQL Data Types and Constraints

Data TypeDescription
BIGINTLarge integer numbers
TEXTLong character strings
TIMESTAMPDate and time with microsecond precision
UNIQUEEnsures that each value in a column is unique
CHECKValidates data based on a specified condition

PostgreSQL Query Language (SQL)

PostgreSQL also uses SQL as its query language, offering similar functionality to MySQL but with additional features and optimizations.

Comparison of MySQL and PostgreSQL

SpeedGenerally faster for simple queriesFaster for complex queries
ScalabilitySuitable for medium to large databasesSupports very large databases
ExtensibilityLimited extensibility optionsHighly extensible with plugins and modules

Advantages and Disadvantages of Relational Databases


  • Structured and organized data storage
  • Data integrity and consistency
  • Efficient querying and data retrieval


  • Can be complex to design and maintain
  • Limited flexibility for unstructured data
  • Vertical scaling can be expensive

When to Use Relational Databases

Relational databases are ideal for applications that require:

  • Storing structured and interrelated data
  • Maintaining data integrity and consistency
  • Efficient querying and reporting

Next Up: Document Databases (MongoDB)

In the next session, we'll explore the world of document databases, specifically MongoDB. Follow us to learn about storing and querying unstructured data with flexibility and scalability.