Refreshing SQL knowledge
Used RDMS: PostgreSQL
What is PostgreSQL?
PostgreSQL is an object-relational database management system (ORDBMS) based on POSTGRES, Version 4.2, developed at the University of California at Berkeley Computer Science Department. POSTGRES pioneered many concepts that only became available in some commercial database systems much later.
PostgreSQL is an open-source descendant of this original Berkeley code. It supports a large part of the SQL standard and offers many modern features:
- complex queries
- foreign keys
- triggers
- views
- transactional integrity
- multiversion concurrency control
Also, PostgreSQL can be extended by the user in many ways, for example by adding new
- data types
- functions
- operators
- aggregate functions
- index methods
- procedural languages
And because of the liberal license, PostgreSQL can be used, modified, and distributed by anyone free of charge for any purpose, be it private, commercial, or academic.
Instruction to practice on Ubuntu console:
Run below commands to practice queries
sudo su postgrespsql- Run sql commands now
Tutorial I followed:
- https://www.postgresql.org/docs/9.1/index.html
- https://www.sqltutorial.org/
- https://www.postgresqltutorial.com/postgresql-getting-started/
Topics
- Create Database
- Create Table
- Insert Query
- General SELECT query
- SQL-DISTINCT
- SQL-ORDER-BY
- SQL-LIMIT