What to Do When You Have Nothing

Inside any database management system (DBMS), one can designate a specific data item as “null.” The null represents the “existence” of a non-value, the nonexistence of a value, or?nothing. This sounds a bit like an oxymoron, a nonvalue value, but there it is. Each DBMS has its own implementation of null support, so what it does to be able to share with you that “there is no value” can differ. For example, rather than a value, there may be a group of bit flags associated with an individual data element, with one of those bits being an “I am null” flag. And because every DBMS has its own way of doing this, it is best not to think that by using a null, one is greatly saving on space usage. Space may be saved, or maybe not so much.