PostgreSQL is a free, open-source SQL database. It’s an alternative to MySQL and is used by small projects as well as larger companies.
Learning the Basics
59 Best Resources for Learning SQL: A large list of other places to learn SQL
19 Best Database Books: a list of books on database-related topics
SQL Roadmap: a guide on SQL topics from beginner to advanced.
PostgreSQL vs MySQL: An analysis of the differences between PostgreSQL and MySQL.
Why Use Postgresql?: An article explaining why you may want to use PostgreSQL.
Basic SQL Statements
SELECT Statement Guide: view data in a table
INSERT Statement Guide: add data to a table
UPDATE Statement Guide: modify data in a table
DELETE Statement Guide: remove data from a table
WHERE Clause: filter data from your query
ORDER BY Clause: specify the order of the results of a Select query
GROUP BY: allows you to group data by values in a column and use aggregate functions
HAVING Clause: allows you to filter data after a group has been applied
DISTINCT: eliminate duplicate rows from your results
Create Table guide: create a new table on the database
Alter Table guide: make changes to an existing table
Drop Table guide: remove a table from the database
Truncate Table guide: remove all data from a table
Joins guide: a guide to joins which are how you combine multiple tables together in a query
One to One joins (video): definition of this join type and an example
One to Many joins (video): definition of this join type and an example
Many to Many joins (video): definition of this join type and an example
Self Join (video): definition of this join type and an example
There are many more objects in a database besides tables. Learn all about them in these guides.
Indexes: a guide to Indexes in SQL
Constraints: rules that can be set on your data
Keys: surograte, natural, primary, foreign, composite, and more
Stored Procedures: a guide to stored procedures in SQL
Views and Materialised Views: objects that let you view data in certain ways
Database Schema: an explanation of this term
Temporary Tables: what it is and how to create one
More features and topics in SQL and PostgreSQL database.
Glossary of Terms: A definition of many terms used in SQL and database development
Data Types: a guide to data types in many different databases
Interview Questions and Answers: a list of 69 interview questions and answers, plus interview tips
DML, DDL, and TCL: a list of SQL commands and what DDL, DML, and TCL mean
Aliases: A guide to column aliases and table aliases in SQL
Subqueries: a guide to subqueries, what they are, and many different examples.
Limiting Results: a guide to SQL row limiting and Top-N queries
CTE (WITH Clause): a guide to Common Table Expressions (CTEs) aka the WITH clause
Transactions and Isolation Levels: an explanation of transactions in SQL and what isolation levels are
Concatenate: what concatenation is and how to do it in SQL
Booleans: how SQL handles booleans and how you can implement them
Wildcards: An explanation of what wildcards are and how to use them
Null: a guide on what NULL is and how to handle them in SQL
Data Warehouses: an in-depth guide to data warehouses
Comments: a guide to comments in SQL and why they can help
Database Version Control, CI, and CD: An in-depth guide on database version control, continuous integration, and continuous deployment
A collection of articles detailing how to do common tasks in SQL queries.
Select Rows with a Max Value: how to select rows with a maximum value for a column
List Tables in a Database: how to list all the tables in a database or a schema
Escape Single Quotes: how to escape single quotes in SQL
Remove Duplicate Records: how to remove duplicate records in SQL