What to do with the older database?

Question

I am assigned in a project where I need to work with a medium database. When I open that database I saw that the database is not correctly made and it MUST have more tables than it should be.No normalization is applied even !

But problem is the database has a medium scale of data of almost 500 users. when I will break the older database, the older users will loss their data.

But I must copy this data to the newly formatted table of the new database.(But all field may not match.) I think there is no tool to automate it, is there any?

Is there any best practice to follow to do such type of work?

Answer 1

Is the schema really a problem or do you just want to fix it because it's not 3rd normal form?

Anyways, I'd create an entirely new database with the desired, normalized schema and write some import routines.

If the database was / is heavily used, I'd create some views to maintain read compatibility (the views would have the same names as the former tables and the same columns), that way all you have to change are the insert / update parts and ofc. the connection strings.

Answer 2

The question beeing asked is:

Is there any tool that can transform a non-normalized database into a normalized database while preserving all its contents.

The answer is: no.

You have to fine-tune the database optimization to your needs.