QuerySets and aggregations in Django

The guide explores the use of Django's object-relational mapper (ORM) to perform both basic and advanced database queries using QuerySets. It explains how QuerySets can be used to retrieve, filter, and order objects without immediate database access, emphasizing methods like `get()`, `filter()`, `first()`, `last()`, `latest()`, and `earliest()`. The guide also covers field lookups for specifying SQL WHERE clauses, the use of chaining filters for complex queries, and advanced operations such as set operations with `union()`, `intersection()`, and `difference()`, as well as Q objects for complex conditionals. Additionally, it discusses using F objects for in-database calculations, performing raw SQL queries with `raw()` and `connection.cursor()`, and obtaining raw SQL from QuerySets. The text concludes by discussing aggregate operations, grouping with `values()` and `annotate()`, and using the HAVING clause to filter groups, all aimed at improving database interaction within Django applications.