Entity Framework Core Interview Question #78

What are the Up and Down methods in an EF Core migration?

Migrations, Database Schema & Data Management Mid-Level Intermediate

Quick Interview Answer

The Up method describes how to move the database forward to the migration's schema state. The Down method describes how to reverse that migration when a rollback is supported.

Detailed Explanation

The Up method describes how to move the database forward to the migration's schema state. The Down method describes how to reverse that migration when a rollback is supported.

For example, Up may add a column and Down may remove it. Some operations cannot be reversed safely without losing data, so a generated Down method should not be assumed to provide a complete business rollback strategy.

Production rollback planning must consider both application code and data changes.

Code Example

protected override void Up(MigrationBuilder migrationBuilder)
{
    migrationBuilder.AddColumn<string>(
        "Sku", "Products", maxLength: 50, nullable: true);
}

protected override void Down(MigrationBuilder migrationBuilder)
{
    migrationBuilder.DropColumn("Sku", "Products");
}