Asp.net core ef migration command11/10/2023 ![]() ![]() Table.PrimaryKey("PK_Enrollment", x => x.EnrollmentID) StudentID = table.Column(nullable: false), ![]() Table.PrimaryKey("PK_Student", x => x.ID) ĮnrollmentID = table.Column(nullable: false) Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.Identit圜olumn),įirstMidName = table.Column(nullable: true),ĮnrollmentDate = table.Column(nullable: false) Table.PrimaryKey("PK_Course", x => x.CourseID) Protected override void Up(MigrationBuilder migrationBuilder)ĬourseID = table.Column(nullable: false), Public partial class InitialCreate : Migration The Down method deletes them, as shown in the following example: using System The Up method of the InitialCreate class creates the database tables that correspond to the data model entity sets. This migrations code is in the Migrations\_InitialCreate.cs file. The EF Core migrations add command generated code to create the database. Run the app and verify that the database is seeded. In Program.cs, delete the following line: () It's designed for testing or rapid prototyping where the database is dropped and re-created frequently.įrom this point forward, the tutorials will use migrations. EnsureCreated doesn't create a migrations history table and so can't be used with migrations. This tutorial series started by using EnsureCreated. Make sure the command prompt is in the project folder, and run the following commands: dotnet ef migrations add InitialCreate Run the following commands in the PMC: Add-Migration InitialCreate SQLite EF Core Database Provider Limitations.For more information, see the following resources: Instead, this tutorial drops and re-creates the database whenever an attempt to apply a migration would fail. Writing database-specific code of this type is outside the scope of this tutorial. Copying data from the old table to the new table.The code goes in the Up and Down methods for a migration and involves: The workaround for the SQLite limitations is to manually write migrations code to perform a table rebuild when something in the table changes. If a migration is created to remove a column, the ef migrations add command succeeds but the ef database update command fails. For example, adding a column is supported, but removing a column is not supported. However, migrations only does the kinds of changes that the database engine supports, and SQLite's schema change capabilities are limited. Migrations updates the database schema to match changes in the data model. This tutorial uses the Entity Framework Core migrations feature where possible. Rather than dropping and recreating the database when the data model changes, migrations updates the schema and retains existing data. The EF Core Migrations feature solves this problem by enabling EF Core to update the DB schema instead of creating a new database. The app can't start with a test DB each time a change is made (such as adding a new column). When the app is running in production, it's usually storing data that needs to be maintained. This approach to keeping the DB in sync with the data model works well until the app needs to be deployed to production. The DbInitializer class then runs to seed the new database. The next time the app runs, the call to EnsureCreated re-creates the database to match the new data model. Each time the data model changes, the database needs to be dropped. This tutorial series started by configuring the Entity Framework to create the database if it doesn't exist. Each time the model changes, the model gets out of sync with the database. When a new app is developed, the data model changes frequently. This tutorial introduces the EF Core migrations feature for managing data model changes. ![]()
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