SQL Relationships & Joins

In today's lecture, Harkirat revisits the Fundamentals of SQL, with a particular focus on the crucial concepts of relationships and transactions in SQL databases. The session provided a deeper understanding of how to structure and query relational data using joins, and explored the various types of joins available in SQL.

Recap

Before diving into advanced topics such as "Relations, Transactions, and Join Queries in SQL Databases," it's crucial to have a solid foundation in the basics of SQL and database management. Here's a detailed recap of the previously covered topics:

Types of Databases

Relational (SQL) Databases: Organize data into tables consisting of rows and columns. Each table represents a relation, and the rows hold individual records. Popular relational database management systems (RDBMS) include MySQL, PostgreSQL, Microsoft SQL Server, and Oracle Database[1][2].
Non-relational (NoSQL) Databases: Use different data models for storing, managing, and accessing data. Common models include document-oriented, key-value, graph, and wide-column stores. NoSQL databases are designed for flexibility, scalability, and high performance with unstructured or semi-structured data[2].

Why Not NoSQL

NoSQL databases offer schema-less data storage, which is beneficial for rapid development and handling large volumes of unstructured data. However, the lack of a strict schema can lead to data inconsistency and challenges in enforcing data integrity as applications grow[1].

Why SQL?

SQL databases are preferred for applications requiring strict data integrity, complex transactions, and relationships between data entities. They support ACID (Atomicity, Consistency, Isolation, Durability) properties, ensuring reliable transaction processing. SQL databases are ideal for applications like e-commerce platforms and financial systems where data consistency is critical[1][2].

Creating a PostgreSQL Database

Using psql: A terminal-based front-end to PostgreSQL that allows for interactive command execution and database management.
Using Docker: Running PostgreSQL in a Docker container for development purposes.

Using `psql`

psql is a powerful tool for interacting with PostgreSQL databases, allowing users to execute SQL queries, manage database objects, and view data directly from the terminal[1].