Optional Parameter (null valued passed)

[mswilson16]

Hi All,

Working on a report at the minute. It has a list of unique keys such as A01, A02, A03, A04, A05, B01, B02, B03 etc etc...

What I want to be able to do is have two parameter fields (StartVal and FinishVal) so that I can pass a parameter for all records, from start to a point, from a point to finish, or just a selection.

e.g. If a value is not passed for StartVal then I want it to take for granted that it starts from the beginning.

I have search high and low and can not find anything on the forums.

Thanks in advance

Mswilson

 

[synapsevampire]

Many things alter the approach to this, starting with the version of your software and the database being used, please remember to post the basics.

A common means for doing this is to set a default value for the parameter such as "All", and then code for it in the record selection formula, as in:

(
{?MyParm} = "all"
or
{table.field} in {?MyParm}
)

This will work if you're using Crystal, however if you're passing parameters from an application, and you *can* pass a null, then you'll have to code for it as in:

(
(
isnull({?MyParm})
or
{?MyParm} = "all"
)
or
{table.field} in {?MyParm}
)

Note that NULL checking must be the first thing in a formula.

-k