Stage 2 · Lesson 9 of 10

Django ORM or SQLAlchemy with Alembic

comes with its own and system. Change a model, then run python manage.py makemigrations to generate a migration file, and migrate to apply it. With , the usual pair is for models and queries, and Alembic for migrations.

There, alembic revision --autogenerate drafts a script and alembic upgrade head applies it. Either way, commit the migration files and read what they will do. Use sqlmigrate, or Alembic's offline mode, to see the actual SQL.

Common trapa renamed field: Django asks whether you meant a rename, but Alembic autogenerate reads it as a dropped column plus a new one. Applied blindly, that deletes the data.

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Resources for this stage

Start with· follow one of these

CoursePaid
Grokking Relational Database Design and Modeling
Design Gurus · Intermediate · $98 one-time
The modelling and normalisation decisions that stay with a codebase for years
CourseFree
CS50's Introduction to Databases with SQL
Harvard University · Beginner
Free course from querying through schema design, indexes, transactions and scaling

Practise

Grokking SQL for Tech InterviewsPaid
Structured SQL practice on joins, grouping and subqueries once the basics feel easy
PostgreSQL Exercises
Free SQL drills on one real schema, from simple selects up to recursive queries

Also worth your time

Database Indexing Explained: B-Tree, Hash, Bitmap, R-Tree, and When to Use Each (opens in a new tab)Read
B-tree and composite indexes, plus the leftmost-prefix rule that trips people up
Grokking Database Fundamentals for Tech InterviewsGo deeperPaid
What sits under your queries: storage engines, transactions and isolation levels