👆 💪 🔎 🖼 ⚗ FastAPI 🏗 📄 ⚪️➡️ [🏗 ⚡ - 📄](../project-generation.md){.internal-link target=_blank}. 🎯 <a href="https://github.com/tiangolo/full-stack-fastapi-postgresql/tree/master/src/backend/app/alembic/" class="external-link" target="_blank"> `alembic` 📁 ℹ 📟</a>.

### ✍ 🔗

🔜 ⚙️ `SessionLocal` 🎓 👥 ✍ `sql_app/database.py` 📁 ✍ 🔗.

Although the hierarchical dependency injection system is very simple to define and use, it's still very powerful.

You can define dependencies that in turn can define dependencies themselves.

In the end, a hierarchical tree of dependencies is built, and the **Dependency Injection** system takes care of solving all these dependencies for you (and their sub-dependencies) and providing (injecting) the results at each step.

You can find an example of Alembic in a FastAPI project in the templates from [Project Generation - Template](../project-generation.md){.internal-link target=_blank}. Specifically in <a href="https://github.com/tiangolo/full-stack-fastapi-postgresql/tree/master/src/backend/app/alembic" class="external-link" target="_blank">the `alembic` directory in the source code</a>.

### Create a dependency