Sync data to database with Entity-Framework Core

We already know how to add data to database. That's simple: _dbContext.MyDbSet.Add(myObject); But there may already exists some data in the database. We need to delete the obsolete data, and try to add the missing data. For example, I have some numbers: 1, 1, 2, 2, 3, 3 While in the database there is: 1, 1, 1, 5 To seed the database to the way we expected, we shall delete the first 1 and  …