Need your expertise. Please advise. There's old table which already released to Production. It's already migrated and had related 2 recorded on the list of migrations ~IRM.SIMSDB\Migrations. In recent, we want to make four changes on this table. including A column, A decimal type field, it needs to be changed its decimal points from 2 to 4 B column B field needs to be removed from the table C column C field needs to be rename its name to C2 from C1 Add a new column D as decimal type all other data fields should stay the same. So, please advise a best solution to migration this old table. e.g. Add-migration and Update-Database or make code change at Configuration set AutomaticMigrationsEnabled = true or something else.

Hi JoannLiao-4647, I suggest you use existing schema as a starting point. First create an initial blank migration, then you can add migrations for any new changes. Run the Add-Migration InitialCreate –IgnoreChanges command in Package Manager Console. This creates an empty migration with the current model as a snapshot. More details you can refer to this document . Best Regards, Daniel Zhang If the response is helpful, please click " Accept Answer " and upvote it. Note: Please follow the steps in our documentationto enable e-mail notifications if you want to receive the related email notification for this thread.

DuaneArnold-0443, I do have administrator role on Database. If U use DBA tools to do the migration, I am much concerns any possible confliction or violation at CODE-FIRST base the application to Start up?

DuaneArnold-0443 I am hands-on programming on SQL for many years. Last week, I did manually changed on SQL to manipulating the data field to be with decimal digit number from 2 to 5. I was wondering whether this approach is OK? Whether this kind of manual change via SQL , it may cause confliction with EF migration or not.

Code First Migrations - Package Manager Console Host Version 5.9.1.0

Joann Liao 21

Need your expertise. Please advise.

There's old table which already released to Production. It's already migrated and had related 2 recorded on the list of migrations ~IRM.SIMSDB\Migrations.

In recent, we want to make four changes on this table. including

A column, A decimal type field, it needs to be changed its decimal points from 2 to 4
B column B field needs to be removed from the table
C column C field needs to be rename its name to C2 from C1
Add a new column D as decimal type

all other data fields should stay the same.

So, please advise a best solution to migration this old table. e.g. Add-migration and Update-Database or make code change at Configuration set AutomaticMigrationsEnabled = true or something else.

Joann Liao 21 Reputation points

2021-04-18T20:57:06.867+00:00
I wanted to keep neat for these files under the list IRM.SIMSDB\Migrations

` Will it be OK to delete these two related files/records, then, run Add-Migration thisTableNameScript? Or, any better solution

Thanks.
Duane Arnold 3,211 Reputation points

2021-04-19T20:44:13.173+00:00

When did an ORM such as EF become a DBA tool? Maybe, you should use DBA tools to do the migration or a have DBA do it for you.

3 answers

Daniel Zhang-MSFT 9,626 Reputation points

2021-04-19T02:32:24.74+00:00

Hi JoannLiao-4647,
I suggest you use existing schema as a starting point.
First create an initial blank migration, then you can add migrations for any new changes.
Run the Add-Migration InitialCreate –IgnoreChanges command in Package Manager Console. This creates an empty migration with the current model as a snapshot.
More details you can refer to this document.
Best Regards,
Daniel Zhang

If the response is helpful, please click "Accept Answer" and upvote it.

Note: Please follow the steps in our documentationto enable e-mail notifications if you want to receive the related email notification for this thread.
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Joann Liao 21 Reputation points

2021-04-19T13:48:58.863+00:00

Okay. I will restore database to test site, and take your suggestion on my test environment.

PM> Add-Migration InitialCreate –IgnoreChanges

Yesterday, I had done the following steps. It might cause data lost.

PM> Update-Database
Specify the '-Verbose' flag to view the SQL statements being applied to the target database.
No pending explicit migrations.
Applying automatic migration: 202104191341250_AutomaticMigration.
Automatic migration was not applied because it would result in data loss. Set AutomaticMigrationDataLossAllowed to 'true' on your DbMigrationsConfiguration to allow application of automatic migrations even if they might cause data loss. Alternately, use Update-Database with the '-Force' option, or scaffold an explicit migration.
PM> Update-Database -Force

Daniel Zhang-MSFT 9,626 Reputation points

2021-04-20T06:10:07.1+00:00

Hi @Joann Liao ,
You can also try to specify the -Script flag to write the changes into the script instead of the application, and then hand over the SQL script to the DBA.
Here is a useful document.
Best Regards,
Daniel Zhang
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Joann Liao 21 Reputation points

2021-04-19T20:52:15.457+00:00

DuaneArnold-0443,

I do have administrator role on Database. If U use DBA tools to do the migration, I am much concerns any possible confliction or violation at CODE-FIRST base the application to Start up?
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Duane Arnold 3,211 Reputation points

2021-04-20T16:41:20.56+00:00

DBA tools are independent of whatever EF an ORM acting as some kind of DBA tool, like scripting the database changes and applying them to another database. You are using EF too much as a DBA tool like it's a crutch. You should learn how to be a programmer with basic DBA skills.
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Joann Liao 21 Reputation points

2021-04-20T17:35:40.303+00:00

DuaneArnold-0443

I am hands-on programming on SQL for many years. Last week, I did manually changed on SQL to manipulating the data field to be with decimal digit number from 2 to 5. I was wondering whether this approach is OK? Whether this kind of manual change via SQL , it may cause confliction with EF migration or not.
Please sign in to rate this answer.
Duane Arnold 3,211 Reputation points

2021-04-20T20:45:30.35+00:00

I don't fool with EF migrations, but I doubt that changing the table schema of a database table is going to cause a problem with migrations as long as migrations are aware of the changes. If you change the table schema and change the EF model used in a program manually to match the schema, one doesn't need the EF migration to do anything.

EF is an ORM, and IMHO, it's not a DBA tool. Developers use EF as a DBA tool and when it fails, they are stuck and don't know what to do without it, because he or she never took the time to learn basic DBA skills.
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