EF Core migrations

Migrations capture schema changes as versioned C# files—like Django migrations. They keep databases aligned across dev, staging, and production environments.

Workflow

1. Install tools: dotnet tool install --global dotnet-ef
2. Change entity classes or Fluent API configuration
3. dotnet ef migrations add AddProductTable
4. dotnet ef database update applies to the database

Migration files

Migrations/
  20240528120000_AddProductTable.cs
  AppDbContextModelSnapshot.cs

Commit migrations to source control—never hand-edit production schema without a matching migration.

Important interview questions and answers

1. Q: migrations add vs database update?
   A: add generates migration code from model diff; update applies pending migrations to the DB.
2. Q: Failed migration in production?
   A: Restore backup, fix forward migration, test on staging—avoid silent manual DDL.

Self-check

1. Which command creates a new migration file?
2. Should migration files be committed to git?

Tip: Run dotnet ef migrations add after every entity change and commit migration files—never hand-edit production tables without a matching migration.