When moving data from either a homegrown application or even a pre-existing Dynamics365 system there are few tricks that can save you a great deal of time and take your project beyond simply completing the data migration and to instead making it a cornerstone in the success of your migration to Dynamics365. I’ve done a number of data migrations ranging from the small (less than 25,000 records from one database) to the larger (greater than 1,000,000+ records from a variety of databases).
Whether you are using tools like Scribe or Kingsway or building your own application – you should always use the available SDKs and not go to the database. In writing that I feel as though as this is slowly becoming a double-negative as you cannot access the database directly for cloud instances of Dynamics365.