Migrations for schema changes in Express - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a migration in the context of database schema changes?

A migration is a set of instructions that change the database structure, like adding or removing tables or columns, to keep the database in sync with the application code.

beginner

Why are migrations important in Express applications?

Migrations help manage database changes safely and consistently, allowing developers to update the schema without losing data or causing errors.

intermediate

Name a popular tool used with Express for managing migrations.

Sequelize CLI is a popular tool that helps create, run, and undo migrations in Express apps using Sequelize ORM.

intermediate

What does the 'up' function do in a migration file?

The 'up' function defines the changes to apply to the database schema, like creating tables or adding columns.

intermediate

How does the 'down' function in a migration file help during development?

The 'down' function reverses the changes made by the 'up' function, allowing you to undo migrations if needed.

What is the main purpose of a migration in Express apps?

A To style the application

B To write frontend code

C To update the database schema safely

D To handle user authentication

Migrations are used to update the database schema safely and consistently.

Which tool is commonly used with Express for migrations?

A Sequelize CLI

B React Router

C Webpack

D Express Generator

Sequelize CLI is a popular tool for managing migrations in Express apps using Sequelize.

What does the 'up' function in a migration file do?

A Handles user input

B Reverts schema changes

C Runs server code

D Applies schema changes

The 'up' function applies schema changes like creating or modifying tables.

What is the role of the 'down' function in migrations?

A To apply new schema changes

B To undo schema changes

C To start the Express server

D To connect to the database

The 'down' function undoes the changes made by the 'up' function.

Why should migrations be used instead of manual database changes?

A They keep schema changes consistent and reversible

B They are faster to write

C They improve frontend performance

D They replace the need for a database

Migrations keep schema changes consistent, trackable, and reversible, avoiding errors.

Explain what a migration is and why it is useful in Express applications.

Think about how you change your database structure without breaking your app.

Describe the roles of the 'up' and 'down' functions in a migration file.

One function moves forward, the other moves backward.