They're different, and they mean different things. NULL means "I don't know this", whereas "" means "I know this is empty". Data display with NULL != "" is ea

They're different, and they mean different things. NULL means "I don't know this", whereas "" means "I know this is empty". Data display with NULL != "" is easy, do what SSMS does and italicise/otherwise highlight the NULL. What problems does "" being different to NULL cause?