Change the word "migrate" to "re-write."

Make darn sure that the economic justification is really there before you begin, because that Microsoft salesman ain't gonna be nowhere nearby when you write the code.
Microsoft has architected the entire dot-net system (of course) to sell
Microsoft server licenses, but that does not mean that you
have to use their database. And maybe your first step should be to change only one part of the system at a time. No, maybe the
first step should be to enumerate all the ultimately-compelling reasons why the system absolutely
cannot be left the way it is; why all of the development effort that went into it must now be
scrapped. "Warm fuzzy feelings" left by a skilled FUD-artist don't count.
Ahem... just checking.
There are various "data pump" programs out there which will handle ordinary data-type conversions but you will probably have to translate the schema (DML) manually. You'll do it twice: once to populate the database with a set of test-data; the second to go live with it.
This is
such a fundamental change that I'll once again stress:
the Microsoft salesman who may have persuaded your boss-of-boss to do this, won't be anywhere around after the license agreement has been sold. But your
business (yours,
not his...) will rely upon that system all the while. Eyes wide open, friend... eyes wide open.
