How to rename a database column in Entity Framework 5 Code First migrations without losing data?

Question

I got the default ASP.NET MVC 4 template successfully running with EF 5.0 Code First Migrations. However, when I update a model property name, the corresponding table column data is dropped by EF 5.0.

Is it somehow possible to rename the table column without dropping data in an automated way?

score 121 · Accepted Answer · answered Nov 29 '12 at 00:41

121

Manually edit the Up and Down methods of the migration to use the RenameColumn method to replace the AddColumn and DropColumn that it automatically generates for you.

answered Nov 29 '12 at 00:41

Josh Gallagher

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Be careful with table names which have dots in them. `RenameColumn` generates a `sp_rename` T-SQL statement which uses uses `parsename` internally which has some limitations. So if you have a table name which has dots in it e.g. "SubSystemA.Tablename" then use: `RenameColumn("dbo.[SubSystemA.Tablename]", "OldColumnName", "NewColumnName");` – Ilan May 16 '13 at 08:46
I think this answer assumes you have `AutomaticMigration = true` Then you execute command `Add-Migration renameColumnXXX` . After that inspect the generated migration file and delete the `DropColumn` and `AddColum` – RasikaSam Nov 04 '20 at 01:34
1

For EF core you can use like this, `migrationBuilder.RenameColumn(name: "oldname",table: "tablename",newName: "newname",schema: "schema");` https://learn.microsoft.com/en-us/dotnet/api/microsoft.entityframeworkcore.migrations.migrationbuilder.renamecolumn?view=efcore-5.0 – Chamika Sandamal Mar 23 '21 at 07:19

score 47 · Answer 2 · edited May 23 '17 at 12:03

As already said, replace the AddColumn and DropColumn that is automatically generated with RenameColumn.

Example:

namespace MyProject.Model.Migrations
{
    using System;
    using System.Data.Entity.Migrations;

    public partial class RenameMyColumn : DbMigration
    {
        public override void Up()
        {
            // Remove the following auto-generated lines
            AddColumn("dbo.MyTable", "NewColumn", c => c.String(nullable: false, maxLength: 50));
            DropColumn("dbo.MyTable", "OldColumn");

            // Add this line
            RenameColumn("dbo.MyTable", "OldColumn", "NewColumn");
        }

        public override void Down()
        {
            // Remove the following auto-generated lines
            AddColumn("dbo.MyTable", "OldColumn", c => c.String(nullable: false, maxLength: 50));
            DropColumn("dbo.MyTable", "NewColumn");

            // Add this line
            RenameColumn("dbo.MyTable", "NewColumn", "OldColumn");
        }
    }
}

Jess · Answer 3 · 2017-05-31T12:23:13.850

27

You can get the migration to call RenameColumn for you if you do this:

[Column("NewName")]
public string OldName { get; set; }

Here is the generated migration:

    public override void Up()
    {
        RenameColumn(table: "Schema.MyTable", name: "OldName", newName: "NewName");
    }

    public override void Down()
    {
        RenameColumn(table: "Schema.MyTable", name: "NewName", newName: "OldName");
    }

If you want your property and DB column to be the same name, you can rename the property later and remove the Column attribute.

edited May 31 '17 at 12:23

answered Jan 19 '17 at 19:31

Jess

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And just to throw in another useful tip, you can also run this in the Package Manager Console: `Update-Database -Script`. Then you can get the SQL `sp_rename` command to run at your leisure. :D – Jess Jan 19 '17 at 19:33
1

Preferred approach since the model's property name is also addressed. And I verified an empty migration is generated in the optional 2nd step of renaming the property. – bvj Mar 04 '20 at 22:46

Thảo Frederic · Answer 4 · 2017-07-19T08:31:34.573

you have 2 steps to rename column in code first migration

The first step,you add ColumnAttribute above your column which are changed, and then update-database command

[Column("Content")]
public string Description { set; get; }

The second step,
- add-migration yournamechange command in order to create a partial class DbMigration.
- add into up and down method here

RenameColumn("yourDatabase","name","newName");

public override void Up()
  {
        RenameColumn("dbo.your_database", "oldColumn",          
       "newColumn");
  }


public override void Down()
  {
        RenameColumn("dbo.your_database", "newColumn", 
        "oldColumn");
  }

Because when you connect, your database and model class will communicate via name_column at database and name_type at property method in model above.

score 4 · Answer 5 · answered Oct 27 '12 at 22:33

Now, this answer is based on my knowledge of EF4.3, so I hope the migrations work roughly the same in EF5 :) After you've created a migration, you should be able to add code in the Up and Down methods, between the dropping of the old property and the creation of the new property. This code should move the property data in the correct direction. I've solved it with the SQL() method in where you can enter raw SQL to perform the data move.

In the Up method of the migration:

SQL("update [TheTable] set [NewColumn] = [OldColumn]");

and in the Down() method:

SQL("update [TheTable] set [OldColumn] = [NewColumn]");

The disadvantage of this approach is that you might couple your code with the database you're working with at the moment (since you're writing raw DB-specific SQL). There might be other methods available for data movement as well.

More info available here: MSDN

score 3 · Answer 6 · answered Mar 25 '15 at 00:19

Adding to Josh Gallagher's answer:

In some places the sp_RENAME syntax is described like this:

sp_RENAME 'TableName.[OldColumnName]' , '[NewColumnName]', 'COLUMN'

However, that will actually include the brackets in the new column name.

DbMigration's RenameColumn() method will probably do the same, so avoid using brackets when specifying the new column name.

Also, the auto-generated commands in Up() & Down() include DropPrimaryKey() and AddPrimaryKey() if the column being renamed is part of the primary key. These are not needed when using RenameColumn(). The underlying sp_RENAME automatically updates the primary key if needed.

score 3 · Answer 7 · answered Jul 14 '20 at 08:31

In Entity Framework Core 3.1.1, If you need to rename a column - Add migration as below

migrationBuilder.RenameColumn(
                                name: "oldname",
                                table: "tablename",
                                newName: "newname",
                                schema: "schema");

score 0 · Answer 8 · edited Nov 10 '19 at 06:50

0

like +Josh Gallagher said, you can use up() for doing things like:

public override void Up()
        {

            RenameColumn("dbo.atable","oldname","newname");
            AddColumn("dbo.anothertable", "columname", c => c.String(maxLength: 250));

        }

i've found this a good help in gettin into migration ;)

edited Nov 10 '19 at 06:50

Mansur

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answered Aug 29 '15 at 16:26

womd

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How to rename a database column in Entity Framework 5 Code First migrations without losing data?

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