There can be many negative scenarios based on the application, but, few I can think of are as below.
Duplicate Validation - Make sure that duplicate values can not be stored, unless application allowed it
Null validation - Make sure that null values can not be stored, unless application allowed it
Date Validation - Often times, date that is bing stored with timezone will be wrong. Make sure that we are storing right date by trying out wrong date.
MINUS Query - Run MINUS validation and to make sure that data being stored is right.
Data Cleaning - Add some junk data and make sure that it is removed periodically. If not removed, it will increase the size of the DB.
