The submission process might deserve its own table with more detail than sent/not sent. Otherwise it's a straigtforward boolean, I don't see any use for NULL he

The submission process might deserve its own table with more detail than sent/not sent. Otherwise it's a straigtforward boolean, I don't see any use for NULL here. Edit: Since it's a date, there are valid use cases for nullable timestamps. But only if there is no additional information attached to the event you're saving in the timestamp. Another complication with nullable timestamps is sorting by them, which you often do with timestamps. With nullable ones this can get messy.