posted May 26, 2004 12:02 AM            

In Basic, the random access database is probably the most used.
Look up "random access files" in the PB help file.
You will need to create routines for adding, editing, deleting,
and indexing your database. This is not a trivial task.
I'm not real familiar with pb/dos but here is some sample
code that should be pretty universal (I just typed this in
from the top of my head so it is untested):

' sample code for name and phone number db
' declare our data type - each record is 30 bytes long
type recType
  rName as string * 20
  rPhone as string * 10
end type
function pbmain()
' declare some variables
  local recVar as recType
  local fNum as long
  local fName as string
  local recs as long
' open the data file
  fNum = freefile  'this gives us an available file handle
  fName = "data.dat"
  open fName for random as #fNum len=sizeof(recVar)
' recs variable tells us how many records in the database
' before we add ours to the end
  recs = lof(fNum)/len(recVar)
' populate a record variable with data
  recVar.rName = "Mike Tyson" 
  recVar.rPhone = "3095551212"
' write the data to the database file at the end of the file
  put #fNum,recs+1,recVar
' read the record back from the database file
  get #fNum, recs+1, recVar
  
' print the data
  print recVar.rName
  print recVar.rPhone   
' close the database
  close #fNum
 
end function

This example is very basic but maybe will give you an idea of
where to start.

posted May 26, 2004 01:06 AM            

you will probably want an sql or xml server?? I think?

commented .. just to try to help start topic discusion

posted May 26, 2004 07:15 AM            

quote:

---

information about databases

---

There are many databases that can be used with PB.
Generally these fall into 2 categories: embedded or servers.

Embedded simply means that the database lives with the program
and the program uses it directly. This could be as simple as a
single text file. Candidates you might consider include
Cheetah http://www.planetsquires.com/
Tsunami http://www.trm-ug.com/
Sqlite http://www.sqlite.org/
Powertree http://www.powerbasic.com/products/powertree/
and others (see the PB links page)

These require special code and libraries and the code varies
with the product. The Sqlite database uses a subset of the SQL
syntax. Powertree is not a database per se but a way to use
a file of data and index the file.

Database servers on the other hand are programs which run on a
remote computer and which permit a client program to access data
on the remote computer. Examples include:
Microsoft SQL 2000, SQL 7, and others
MySql http://www.mysql.com/
Oracle
many, many others

These generally are manipulated using ODBC or ADO drives which
require a library for the interface usually provided by
the vendor. A library for your program such as
SQLTools http://www.powerbasic.com/products/sqltools/
and usually data is accessed via SQL (structured query language).

It is also possible to make any embedded database a server by
writing your own server program. A forum contributor has done
this with Tsunami as an example - see http://ttds.greatwebdivide.com/ by Don Dickinson.

quote:

---

i need to know how they work

---

That question is too broad to be specific. But generally a
database provides a means to locate, access, and manipulate data.
Usually this is done by creating an index (or several) that
keep track of various portions of the data.

quote:

---

what i need to do to allow multiple computers modify a database at the same time keeping the information accurate.

---

That requirement favors a database server. Which database server
depends upon a lot of things. If your users are going to connect
to the database server over the Internet then who will host it and
what do "they" offer being of paramount interest. If the host
provides MySql then your program has to use MySql.

If you have to also provide the host resources then you have more
research and analysis to do depending upon your project requirements.

posted May 26, 2004 08:00 AM            

Um, no you don't; you 'can' if you want, but you don't 'need to' do so.

For "regular" files the SHARE and LOCK options of the OPEN statment, as well as the LOCK/UNLOCK functions, and the ERR returned when one computer tries to access a file or portion of a file currently in use by another computer provide everything your need.

That said, this is not particularly easy to code.

If you are using a commercial database, there are options available both the DBMS and through SQL to control access. (Usually not necessary, as most operations on a database are "user-count-agnostic").

MCM

posted May 26, 2004 04:49 PM            

We had a hard time creating a hotmail account for her and
i dont think its fair that she was blocked, but oh well, Dont
worry, this was a quick question and i doubt she will need to
post anymore.

Elias

------------------
Last night i was decided to retreat, Then i decided not to.

posted May 26, 2004 07:30 PM            

best wishes,

posted May 27, 2004 08:08 AM            

You mean, she did register with her real name, real email address and otherwise followed all the published rules, and the webmaster made a unilateral and not doubt divinely inspired decision she was lying?

MCM

posted May 27, 2004 08:22 AM            

quote:

---

Please make sure she knows this is a forum for PowerBASIC,
not "qbasic or any other basic language".

---

posted May 27, 2004 11:19 AM            

It was an honest mistake, since corrected, made on the basis of a
great deal more experience dealing with pseudonyms than anyone would
ever want to acquire, and a wee bit more data than may be obvious.