how automatically reset record in database?

[eherage]

My project has connected to the access.
There is Reseration date and Beginning date in the table of the database.
If the Reservation date is filled,and the Beginning date is not filled(still
null) in 3 days,
the Reservation date of the record must be automatially set null.How?
How to write the code to know the Reservation date is more 3 days before?
And how to reset the record?

[W.G. Ryan eMVP]

What database are you using? If you're using Oracle or SQL Server,I'd do
this server side with a Trigger so that you don't have to depend on the
client app to enforce this rule.
"eherage" <eh*****@discussions.microsoft.com> wrote in message
news:EF**********************************@microsof t.com...

My project has connected to the access.
There is Reseration date and Beginning date in the table of the database. If the Reservation date is filled,and the Beginning date is not filled(still null) in 3 days,
the Reservation date of the record must be automatially set null.How?
How to write the code to know the Reservation date is more 3 days before?
And how to reset the record?

[eherage]

I am student.It is our homework.As we haven't Oracle or SQL Server,I use
Access,because it is simple.

"W.G. Ryan eMVP" wrote:

What database are you using? If you're using Oracle or SQL Server,I'd do
this server side with a Trigger so that you don't have to depend on the
client app to enforce this rule.
"eherage" <eh*****@discussions.microsoft.com> wrote in message
news:EF**********************************@microsof t.com...

My project has connected to the access.
There is Reseration date and Beginning date in the table of the

database.

If the Reservation date is filled,and the Beginning date is not

filled(still

null) in 3 days,
the Reservation date of the record must be automatially set null.How?
How to write the code to know the Reservation date is more 3 days before?
And how to reset the record?