Migrating Db and Entity framework

Question

I have to take data from an existing database and move it into a new database that has a new design. So the new database has other columns and tables than the old one.

So basically I need to read tables from the old database and put that data into the new structure, some data won't be used anymore and other data will be placed in other columns or tables etc.

My plan was to just read the data from the old database with basic queries like

Select * from mytable

and use Entity Framework to map the new database structure. Then I can basically do similar to this:

while (result.Read())
{
    context.Customer.Add(new Customer
    {
        Description = (string) result["CustomerDescription"],
        Address = (string) result["CuAdress"],
        //and go on like this for all properties
    });
}
context.saveChanges();

I think it is more convenient to do it like this to avoid writing massive INSERT-statements and so on, but is there any problems in doing like this? Is this considered bad for some reason that I don't understand. Poor performance or any other pitfalls? If anyone has any input on this it would be appreciated, so I don't start with this and it turns out to be a big no-no for some reason.

there are some db migration tools and you may find it easier to migrate data from your existing database to new one using these tool. — daryal
– daryal, Commented Dec 4, 2013 at 9:28
I would use Sql Server Integration Services or do everything with some sql scripts. — Raphael
– Raphael, Commented Dec 4, 2013 at 13:57

user3083619 · Accepted Answer · 2014-02-24 18:47:29Z

1

Something that you could perhaps also try, is merely to write a new DBContext class for the new target database.

Then simply write a console application with a static method which copies entities and properties from the one context to the other.

This will ensure that your referential integrity remains intact and saves you a lot of hassle in terms of having to write SQL code, since EF does all the heavy lifting for you in this regard.

If the dbContext contains a lot of entity dbsets I recommend that you use some sort of automapper.

But, this depends on the amount of data that you are trying to move. If we are talking terrabytes, I would rather suggest you do not take this approach.

answered Feb 24, 2014 at 18:47

user3083619

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