Question: What is up and down methods in migration?

What is a down migration?

Missing “down” migrations means, that we haven’t migrations at all, and we are back in the early 90′ reverting database from backup or painfully modify the table(s) believing, that everything should go well.

What is up and down in EF?

You can update Up and Down methods for any changes. When we run migrations, Up method will call by default and update the database based on code written in its scope. Down method exactly opposite of Up method. Down method will use when we want to revert our migrations.

How do I use migrate down?

The down method exists to run when the migration is rolled back, e.g: php artisan migrate:rollback will delete the table flights . You are expected to write code to reverse what was done in up , e.g: if up adds a new column; down deletes it. The down method only runs when you roll back the migration.

What is up and down in laravel migration?

A migration class contains two methods: up and down . The up method is used to add new tables, columns, or indexes to your database, while the down method should reverse the operations performed by the up method.

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What is EF migration?

The migrations feature in EF Core provides a way to incrementally update the database schema to keep it in sync with the application’s data model while preserving existing data in the database. … Once a new migration has been generated, it can be applied to a database in various ways.

What is DbContext C#?

A DbContext instance represents a combination of the Unit Of Work and Repository patterns such that it can be used to query from a database and group together changes that will then be written back to the store as a unit. DbContext is conceptually similar to ObjectContext.

What is database update?

Update-Database: Executes the last migration file created by the Add-Migration command and applies changes to the database schema.

What are migrations in rails?

Migrations are a convenient way to alter your database schema over time in a consistent way. They use a Ruby DSL so that you don’t have to write SQL by hand, allowing your schema and changes to be database independent. You can think of each migration as being a new ‘version’ of the database.

What is rake in Ruby on Rails?

Rake is Ruby Make, a standalone Ruby utility that replaces the Unix utility ‘make’, and uses a ‘Rakefile’ and . rake files to build up a list of tasks. In Rails, Rake is used for common administration tasks, especially sophisticated ones that build off of each other.

What is schema RB?

The schema. rb serves mainly two purposes: It documents the final current state of the database schema. Often, especially when you have more than a couple of migrations, it’s hard to deduce the schema just from the migrations alone.

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What does the migrate command do?

Django python manage.py migrate command

migrate executes those SQL commands in the database file. So after executing migrate all the tables of your installed apps are created in your database file. … and using above command, table will be created in the database when we use migrate.