Accepting defaults for a process as complex as moving from MS Access to MS SQL Server should NOT be considered prudent. Unless the data is quite simple, then even using the SSMS import wizard isn't really a good idea. However, Microsoft has made a number of versions of SSMA (aka SQL Server Migration Assistant), where you can specify exactly what your data types need to be and perform the migration in pieces. If the SQL Server side is new, then you can easily wipe out all the new tables data with a series of TRUNCATE statments (or you prep a query or proc to do it), and you can re-do the data part of the migration as many times as needed until you get it right. It's not always obvious as to how to get certain things to happen, but it's not really rocket science, either. NOT using that tool is probably a bad idea.