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Databases in Python
course content

Course Content

Databases in Python

Databases in Python

1. Introduction to SQLite
SQLiteWhat is SQLite3 Library?Connecting to DatabaseCreating a Simple TableChallenge: First Table
2. CRUD
What is CRUD?Creation OperationsRead OperationsUpdate OperationsDelete Operations
3. More About SQLite
PRIMARY KEYData TypesChallenge: Table Design
4. SQLAlchemy
Object–Relational MappingGetting Started with SQLAlchemyData TypesCreating Your First ModelBuilding SQLAlchemy ObjectsReading from DBUpdating to DBDeleting from DB

book
Creating Your First Model

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.

Task
test

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In this task, you are provided with a starting point for defining an SQLAlchemy model. Your job is to complete the model by filling in the missing pieces.

  1. The __tablename__ attribute specifies the table name in the database. Replace the placeholder with the correct table name for the User model.
  2. The id column should be marked as the primary key. Add the correct keyword argument to indicate this.
  3. The username column should be unique, meaning no two users can have the same username. Fill in the missing keyword argument.
  4. The is_active column should have a default value of True. Add the proper argument to set this default value.

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Section 4. Chapter 4
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book
Creating Your First Model

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.

Task
test

Swipe to show code editor

In this task, you are provided with a starting point for defining an SQLAlchemy model. Your job is to complete the model by filling in the missing pieces.

  1. The __tablename__ attribute specifies the table name in the database. Replace the placeholder with the correct table name for the User model.
  2. The id column should be marked as the primary key. Add the correct keyword argument to indicate this.
  3. The username column should be unique, meaning no two users can have the same username. Fill in the missing keyword argument.
  4. The is_active column should have a default value of True. Add the proper argument to set this default value.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 4. Chapter 4
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