Code First Data migration go

I. Setting up Code First Data migration for model changes

1, tools---Library Package Manager, Package Manager console, input "Enable-migrations" or

Enable-migrations-contexttypename Mvc.Models.DataContext

Enable-migrations-contexttypename namespace. Context Name

Note: If correct, the Code first migration has been enabled for Project XXX. ”，

Enable-migrations command creates a migrations folder and Configuration.cs file

2, the Package Manager console, enter "Add-migration Initial" to create an initial migration.

Note: The name "Initial" is arbitrarily named, that is, the field to be added. Used to name the created migration file.

3, Package Manager console, input "Update-database"
4, run the program, update completed.

Second, further
The problem has been solved, so let's take a closer look at this migration approach.
When we add columns (adding entity fields), you don't have to repeat all of the above actions.
1. Only the automaticmigrationsenabled = False in the \migrations\configuration.cs file should be changed to True
2, tools, library Package Manager, Package Manager console, input "Update-database"

Third, when we delete the column (delete entity field), also use the above operation, no success, the report will lose data,

So you can't simply execute "update-database" to complete.

1, execute the command "Add-migration Initial"
2. Execute command "update database"
3, run the program, update completed

Four, very powerful migration

public class Contactcontext:dbcontext
{
Public Contactcontext ()
: Base ("Name=defaultconnection")
{
Automatically create tables if entity has changed to update to table structure
Database.setinitializer<contactcontext> (New Migratedatabasetolatestversion<contactcontext, Reportingdbmigrationsconfiguration> ());
}


protected override void Onmodelcreating (Dbmodelbuilder modelBuilder)
{
Modelbuilder.conventions.remove<pluralizingtablenameconvention> (); The table name is the class name, not the name above with S//the contract that removes the plural table name
Modelbuilder.conventions.remove<includemetadataconvention> (); Do not create edmmetadata table//Prevent shady transactions or visit edmmetadata this table every time
}


Public dbset<city> Cities {get; set;}
Public dbset<area> area {get; set;}
Public dbset<campaign> Campaign {get; set;}
}


Internal sealed class Reportingdbmigrationsconfiguration:dbmigrationsconfiguration<contactcontext>
{
Public Reportingdbmigrationsconfiguration ()
{
automaticmigrationsenabled = true;//changes to any model class will update the DB directly
Automaticmigrationdatalossallowed = true;
}
}

Reference URL

Http://www.cnblogs.com/hugh251325/archive/2013/03/21/2972431.html

Http://www.cnblogs.com/youring2/p/mvc-5-adding-a-new-field.html

http://blog.csdn.net/zy332719794/article/details/8845405

Http://www.ejutuo.com/bbs/thread-3225-1-1.html

Some tips for code first programming in http://www.cnblogs.com/chinabc/archive/2013/01/16/2846062.html MVC

Code First Data migration go