How to delete and recreate from scratch an existing EF Code First database

问题

I am using EF Code First with EF 5 in VS 2012. I use PM update-database command and I have a simple seed method to fill some tables with sample data.

I would like to delete and recreate my x.mdb. The update history seems to be out of sync. If I comment out all my DBSets in my context, update-database runs with no error but leaves some tables in the DB. As I have no valuable data in the DB it seems to the simplest to reset the all thing.

How can I accomplish this?

回答1:

If I'm understanding it right...

If you want to start clean:

1) Manually delete your DB - wherever it is (I'm assuming you have your connection sorted), or empty it, but easier/safer is to delete it all together - as there is system __MigrationHistory table - you need that removed too.

2) Remove all migration files - which are under Migrations - and named like numbers etc. - remove them all,

3) Rebuild your project containing migrations (and the rest) - and make sure your project is set up (configuration) to build automatically (that sometimes may cause problems - but not likely for you),

4) Run Add-Migration Initial again - then Update-Database

回答2:

If you worked the correct way to create your migrations by using the command Add-Migration "Name_Of_Migration" then you can do the following to get a clean start (reset, with loss of data, of course):

1. Update-database -TargetMigration:0

   Normally your DB is empty now since the down methods were executed.

2. Update-database

   This will recreate your DB to your current migration

回答3:

Single Liner to Drop, Create and Seed from Package Manager Console:

update-database -TargetMigration:0 | update-database -force

Kaboom.

回答4:

For EntityFrameworkCore you can use the following:

Update-Database -Migration 0

This will remove all migrations from the database. Then you can use:

Remove-Migration

To remove your migration. Finally you can recreate your migration and apply it to the database.

Add-Migration Initialize
Update-Database

Tested on EFCore v2.1.0

回答5:

How about ..

static void Main(string[] args)
{
    Database.SetInitializer(new DropCreateDatabaseIfModelChanges<ExampleContext>());  
    // C
    // o
    // d
    // i
    // n
    // g
}

I picked this up from Programming Entity Framework: Code First, Pg 28 First Edition.

回答6:

If you created your database following this tutorial: https://msdn.microsoft.com/en-au/data/jj193542.aspx

... then this might work:

1. Delete all .mdf and .ldf files in your project directory
2. Go to View / SQL Server Object Explorer and delete the database from the (localdb)\v11.0 subnode. See also https://stackoverflow.com/a/15832184/2279059

回答7:

Take these steps:

1. Delete those object which should be deleted from the context // Dbset<Item> Items{get;set;} and in Nuget Console run these commands
2. add-migration [contextName]
3. update-database -verbose

It will drop table(s) that not exist in Context, but already created in database

回答8:

dbctx.Database.EnsureDeleted(); dbctx.Database.EnsureCreated();

来源：https://stackoverflow.com/questions/16035333/how-to-delete-and-recreate-from-scratch-an-existing-ef-code-first-database