Re: Do we really need NULL??

I work for an organisation that stores medical and survey data. For us it is not enough to have simply NULL for missing data - we need to know whether

• value was not applicable for this person or
• value was unreadable on the form for this person or
• value was missing on the form for this person. (and perhaps other varieties of "NULL" in the future)

We store all data in CHAR format, to allow us to store "missing-value codes" in fields. "Standard" PL/SQL procedures in our FORMS applications provide field validation - e.g. that a number is either a valid number,  or a missing value code, and within a certain range, etc. For each table,  we set up a view that decodes each field from CHAR to its appropriate  data type, with the missing value codes being decoded to NULL.

So this is another perspective on "do we need NULLs" : "Yes", and more of them ! Received on Tue Nov 15 1994 - 00:06:07 CET