Can't you just add rows to your Reservations table as the reservations
are made?  Why would you prefill?

It depends a bit on how you represent the information in the program and
how you want to manipulate it.

1:
with a database where you only have search results in program memory you
just represent it as a reservation table with the information date,
time, timespan, table_num, customer_name etc
you do simple seraches which returns some rows which you add in an
ArrayList and display. You could search for all reservations on a
certain date or on a date for table num x, etc

2:
if you want to hold it in memory (todays and tomorrows reservations) and
perform in-memory searches you need to create a memory representation
that can perform such operations quickly and easily, ex.

- have an object representing a reservation. it contains the table
number, the date/time and timespan (the timespan depends on the policy
of the restaurant as some restaurants only have one reservation for the
table for the whole evening, while others have several)
- then you have two indexes: date and table which will hold a reference
to the reservation

You would of course store it aswell, but for that you only need to
serialise it to either a file format, binary or xml or you could use
javaspace, bbdb, or a sql or oo db.

/tom