Creating manually

You can create a new migration using CLI by specifying the name and location of the migration:

npx typeorm migration:create <path/to/migrations>/<migration-name>

For example:

npx typeorm migration:create src/db/migrations/post-refactoring

After you run the command you can see a new file generated in the src/db/migrations directory named {TIMESTAMP}-post-refactoring.ts where {TIMESTAMP} is the current timestamp when the migration was generated.

Now you can open the file and add your migration sql queries there. You should see the following content inside your migration:

import { MigrationInterface, QueryRunner } from "typeorm"

export class PostRefactoringTIMESTAMP implements MigrationInterface {
    async up(queryRunner: QueryRunner): Promise<void> {}

    async down(queryRunner: QueryRunner): Promise<void> {}
}

There are two methods you must fill with your migration code: up and down. up has to contain the code you need to perform the migration. down has to revert whatever up changed. down method is used to revert the last migration.

Inside both up and down you have a QueryRunner object. All database operations are executed using this object. Learn more about query runner.

Let's see what the migration looks like with our Post changes:

import { MigrationInterface, QueryRunner } from "typeorm"

export class PostRefactoringTIMESTAMP implements MigrationInterface {
    async up(queryRunner: QueryRunner): Promise<void> {
        await queryRunner.query(
            `ALTER TABLE "post" RENAME COLUMN "title" TO "name"`,
        )
    }

    async down(queryRunner: QueryRunner): Promise<void> {
        await queryRunner.query(
            `ALTER TABLE "post" RENAME COLUMN "name" TO "title"`,
        ) // reverts things made in "up" method
    }
}