For DateTime fields, I want to be able to default to the current DateTime, or enter something like NOW() when editing a row. I found this issue which discusses a setting to handle this:
https://www.heidisql.com/forum.php?t=10103
However, this says that it only works with NULLs. If I duplicate a row that already had a value and then make it blank, I get 0000-00-00 00:00:00 in the DateTime field.