问题
I am using MVC 5 with NET Framework 4.5.1. with Code-first. I am also using Migrations with the SQL 2012 server and (localdb)\v11.0.
I am in the middle of developing a project using C# and MVC5. During development, I created a lot of new tables in my developmental computer and changed a the "Name" field which I believe the system makes an index for. I added it and deleted it several times.
After that, I added a lot iof new unrelated tables, but for some reason, my migrations started giving me foreign constraint errors due to the indexes for the "Name" field. These errors kept multiplying as I fixed them, so, I decided to revert back to an initial state in the migration, and reset using the current position as a new starting point. I was hoping, that the production table would look at this new starting point in the development db, and resynch itself to the developmental state. I thought that I had read somewhere that the production db matches itself to the developmental db and updates itself. I believe that there is a migration file in the production db which would match itself to the file in the developmental db -that file was clearly out of synch. I have considered deleting the data in it, but I am holding off till I get advice.
Anyway, I changed the name of the migrations directory in the Dev computer and excluded it from the project. Then I reinitialized my tables (using a new db name in my local db) on the dev computer and re-loaded it with the initialization data. It all worked.
Now, I had a new problem, my production db and my developmental db were different, and my migration in the dev computer was setup to create new files whereas the one in the production state was expecting the older migration. Every time I tried to update the production db using the development computer, I kept getting an error that the files existed - which of course they did.
So, I commented out all the create files in my migration file and re-tried. Now, the production db would start, but would not run because the updated code had new fields it was referring to which did not get created in the production db. So, on my production db I started to get errors of all the fields that were missing. I tried to make automatic migrations true as well, that did not work. I am guessing, the only way to fix this is to go in manually and synch the fields one by one.
QUESTION 1: Is there an automatic way to synch (using migrations) the production db and the developmental db so that they become the same same as the developmental db?
QUESTION 2: Keeping in view the above scenario, what would have been a better way to go about to re-set the miggrations with a production db out as well?
回答1:
I found a solution. The folks at Red-Gate have a great SQL tool called the SQL Compare. It compares the database file structures and even makes them EXACTLY the same, at a click of a button.
But, before you use it, be sure you ONLY compare "tables", as opposed to everything which includes "users" and "roles" and a lot more. That is because when you run the software, it backups, deletes and re-creates, and if the roles or users get deleted, the software can no longer access the database and everything gets deleted! Also... MAKE A BACKUP! (I lost all my test data on my first try)
http://www.red-gate.com/products/sql-development/sql-compare/
(This is not a sales plug for the folks at Red-Gate. I dont know them, but their tool helped me immensely - its a good tool, easy to use, and FREE for 14 days! - and I list it here so that anyone else, and I am sure there are many, who may be stuck like me can be helped.)
April 24 2015
Ok. There is more to it after you synch both the databases so that they look exactly alike.
Create a Back up of your production data *
Delete the Migration folder in your developmental folder.
- Enable Migrations again
- Add an initial migration
- Update the local database
Now you have your local completely set up *
Go to the host database
- Find the table called "__MigrationHistory" in Host/Production
- Delete all the data (you want to purge it) ("__MigrationHistory" (Host))
- Now copy all the data from the local "__MigrationHistory" to the hosted "__MigrationHistory" (There will be your one single line i.e. the initial one you created above")
- Now the data has been saved and every thing will be synched and it will work. You can begin development again.
来源：https://stackoverflow.com/questions/27704182/migration-synch-developmental-and-production-databases