Negative stock can be perfectly feasible just because the warehouse choose to stack up their receipt postings until they have time to do them in a batch, but meanwhile the items are placed ready for picking, which menas they are consumed before being received.

The main use of null is to tell whether a value is a positive input or simply a lack of data. For example, test results where zero is a valid input. If you just have a zero rather than a null, does that mean that the user has not entered anything yet or that they have actually entered a zero? If you use a null then you can tell the difference – a null means they haven’t entered a value yet and zero means that they actually typed zero. That way you can verify if all the results have been entered before proceeding.

Can you guess what happened?

To make matters worse, there was a management turf war going on at our end too, which hardly helped. Then we had a consultant on site who resigned mid-project and began working for the customer the next day.

The HR system leaving date is an excellent example for null.

A death date in a family history application opens up the possibility of Null meaning two things – “still alive” or “information not known” (and sometimes it could be either).