no pending explicit migrations

Question

I am using VS2017 pro. I created an MVC5 solution in C# and opened Package Manager Console. In the Entities folder I created a class and marked it up with appropriate annotations. update-database command created the table (and some initial other tables). I created another class in the Entities folder, identical to the first with the same markup, except for the class name and table name.
When I ran update-database it reported "no pending explicit migrations" and did not create the new table.
Why did the first one work and the second one (just a minute after) fail? What do I do to make it create the new table? SQL Server Express, LocalDb. There should not be any problem with the database itself, since the first migration worked, and the second, that did not work, in the same session of the application and Package Manager.

Answer 1

Hi @Jon Jacobs ,
If you are using Code First for data migration, and you modify the Model after executing it once, you can follow the commands below.

1.Enable-Migrations -EnableAutomaticMigrations –Force  

The execution of Enable-Migrations may be interrupted due to an error. At this time, you need to run the parameter-added command -Force.

2.Add-Migration Initial  

The Add-Migration command scaffolds your changes into a cs file. This cs file is placed in the same folder as the configuration file for the DbContext you are targeting.

3.Update-Database -Verbose  

Then you use Update-Database to update the database. Specify the -Verbose flag so that you can see the SQL that Code First Migrations is running.
You can refer to Code migration.

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Best Regards,

ChaoDeng

Answer 2

Thank you, @Chao Deng-MSFT . That was very helpful. I ran the first two commands,
Added a test class:
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Web;

namespace Memberships.Entities
{
[Table("Something")]
public class Something
{
[MaxLength(80)]
public string Title { get; set; }
}
}
I then ran update-database -verbose. The result was strange, including a long hex value:
PM> update-database -verbose
Using StartUp project 'Memberships'.
Using NuGet project 'Memberships'.
Specify the '-Verbose' flag to view the SQL statements being applied to the target database.
Target database is: 'MembershipsDb' (DataSource: (LocalDb)\MSSQLLocalDB, Provider: System.Data.SqlClient, Origin: Configuration).
Applying explicit migrations: [202104221349217_initial].
Applying explicit migration: 202104221349217_initial.
INSERT [dbo].__MigrationHistory
VALUES (N'202104221349217_initial', N'Memberships.Migrations.Configuration', 0x1F8B0800000000000400DD5CDB6EE436127D5F60FF41D0D366E1B47CD919CC1AED044EDBCE1A3BBE60DA13ECDB... etc. , N'6.2.0-61023')

Running Seed method.
PM>