In SQLAlchemy, creating a model involves defining a Python class that corresponds to a table in the database. Each instance of this class represents a row in the table. Let’s walk through a simple example where we create a Comment model for storing user comments.

This defines a Python class called Comment, which represents a table in the database. The class inherits from Base, which enables it to be mapped to a table in the database.

The Comment class, inheriting from Base, defines a table in the database. This allows it to be mapped to a database table using Object-Relational Mapping (ORM).

The id field serves as the primary key, ensuring that each comment has a unique identifier. SQLAlchemy automatically increments the value for each new record.

The id field serves as the primary key, ensuring that each comment has a unique identifier. SQLAlchemy automatically increments the value for each new record.

The created_at field automatically stores the timestamp for when the comment was created. If no value is provided, it is set to the current time using datetime.utcnow, ensuring the timestamp is recorded in UTC.

This line creates all the tables in the database that were defined in the models. It uses the information from the metadata and creates the necessary tables through the connection provided by the engine. This is useful for automatically creating tables if they don't already exist.