@karim came up with a good default behaviour for the CSV import in #1349:

I just want to say something. 😃

Regarding the expected behavior of DB4S when importing empty values from a CSV.

1. If the column has a default value then it gets priority over everything else.
   • This is the default action for SQLite, it fills columns with default values when a value is not given.
   • The column being NOT NULL or not doesn't matter, since a value will be set for it anyway.
   • ✔️ No need for a checkbox, it should be the right thing to do. 👍
2. If the column does not have a default value.
   1. Check if the column does not have NOT NULL, if true:
      • Then just add NULL to it, it should be the default.
      • Be consistent. CSV value is NULL, SQLite table doesn't forbid NULL, so just add NULL.
      • ✔️ Also, no need for a checkbox, and this is what everyone here wants. 🎉
   2. Else if it does have NOT NULL, then we have two options, either:
      1. Fail the import (make sense since you are importing NULL to a NOT NULL column), or
      2. Set a default value for it (e.g. 0 for INTEGER, "" for TEXT)
         • Probably by adding a checkbox to "set default values for empty fields in NOT NULL columns" (need a better wording 😄)

We should implement some rules in the import code to reflect this and maybe add some configuration options to make any deviation from this default an explicit decision by the user.