Subject Re: [ib-support] ISQL and NOT NULL fields
Author Paul Schmidt
On 7 Nov 2001, at 18:15, Ivan Prenosil wrote:

> Which variant do you think is better for ISQL ?
> To show '0' or '' instead of '<null>' (like in current ISQL),
> or to show null as '<null>' (like in WISQL ) ?

A null should show as <null> in ISQL, just as it should in any
utility, the reason being that null really means that a value has not
been set. A good example is a hotel database, which has a
customer table, which includes a checked out date field, if the
person is still staying, then the checked out date is <null>
because it's not known when they are checking out. Of course this
means there is a fast way to tell who is staying, simply select all
customers where the checked out date is <null>. This is really the
purpose behind having nulls in the first place, otherwise you would
need to use a code value, and there isn't always a code value
available. For example on our checked out date, what is a valid
date that doesn't get used? So the fact the field can be null, null
becomes the code value.


Paul Schmidt
Tricat Technologies