Is it possible to make a booking system using delphi/lazarus?
lazarus / 16-Databases

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BITW · 2014-03-30 16:15

I am programming a database(DB) in Lazarus as a project and for
increased complexity have NOT downloaded any additional libraries. The
software is intended to allow customers to check availability of
hiring a villa and them make a booking if the villa is available.

Declaring records and writing them to a file acts as a table for my
DB. Reading/Writing/Deleting the records in my files has been achieved
successfully and I now move on to the point where I use this data to
make bookings. I have 3 tables; Clients Villas Bookings

Now, my problem comes in with the bookings table. How do I make my
application know that a villa has already been booked for the period
in which a new booking wants to be made. (basically double booking
shouldn't be allowed) So far as mentioned, I can only read/write and
delete records in my tables and now move on to the booking stage.
Please ask if further info is needed


I'm thinking of using the Tcalendar but have no idea how to program
with it or even if that is the simple way of doing it. Any tips
please?

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howardpc · 2014-03-30 19:18

One approach would be to loop through all bookings looking for a
potential clash (overlap) of dates with the proposed new booking. A
simple-minded approach might elaborate on something like the
following:

Code: [Select]
interface

TDateRange = record
    startDate: TDateTime;
    endDate: TDateTime;
  end;

  function DatesClash(range1, range2: TDateRange): boolean;


implementation

function DatesClash(range1, range2: TDateRange): boolean;
    // assumes startdate < endDate in data passed in ranges
begin
  if range1.startDate = range2.startDate then
    Result:=True
  else if range1.startDate < range2.startDate then
    Result:=range1.endDate > range2.startDate
  else                      // range1.startDate > range2.startDate;
    Result:=range1.startDate < range2.endDate;
end;

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marcov · 2014-03-30 19:23

Yes. See also http://stackoverflow.com/questions/22746326/is-it-
possible-to-make-a-booking-system-using-delphi-lazarus

In general one would write an SQL query to check if a certain period
is free. (e.g. by searching in a table with an index on start date).
What database are you planning to use?

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BITW · 2014-03-30 20:00

Quote from: marcov on March 30, 2014, 09:23:00 pmYes. See also
http://stackoverflow.com/questions/22746326/is-it-possible-to-make-a-
booking-system-using-delphi-lazarus

In general one would write an SQL query to check if a certain period
is free. (e.g. by searching in a table with an index on start date).
What database are you planning to use?

haha thats my question too  Its fine, @howardpc explained it perfectly

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BITW · 2014-03-30 20:01

Quote from: howardpc on March 30, 2014, 09:18:16 pmOne approach would
be to loop through all bookings looking for a potential clash
(overlap) of dates with the proposed new booking. A simple-minded
approach might elaborate on something like the following:

Code: [Select]
interface

TDateRange = record
    startDate: TDateTime;
    endDate: TDateTime;
  end;

  function DatesClash(range1, range2: TDateRange): boolean;


implementation

function DatesClash(range1, range2: TDateRange): boolean;
    // assumes startdate < endDate in data passed in ranges
begin
  if range1.startDate = range2.startDate then
    Result:=True
  else if range1.startDate < range2.startDate then
    Result:=range1.endDate > range2.startDate
  else                      // range1.startDate > range2.startDate;
    Result:=range1.startDate < range2.endDate;
end;

Thanks, helped a lot and its cool to know we were on the same
wavelength! (Y)

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BigChimp · 2014-03-31 08:59

You could also use TDBF which is part of FreePascal/Lazarus and use
DBase tables to store your details.

You can then filter the records you are interested in looking at:
http://wiki.lazarus.freepascal.org/Lazarus_Tdbf_Tutorial#Index.2Ffilte
r_on_TDateTimes

Good luck with this homework assignment