Databases
lazarus / 16-Databases

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TonyR500 · 2020-06-22 15:57

A question concerning database applications

I have to provide some enhancements to some Delphi applications which
were written more than 20 years ago.I thought I would try to do this
using Lazarus. The data tables in these applications are mainly dBase
DBF files with (possibly) some Paradox files. Some of the applications
use local dbf files i.e they are on one PC only.

Now, I am new to Lazarus and my question is: -
Using Lazarus can I connect Forms to local dBase dbf tables? and if so
how do I do it?
Which dataset and which datasource do I use? Any information regarding
this would be useful.

Many Thanks

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mig-31 · 2020-06-22 16:32

Hi,
please read this wiki arctile
https://wiki.freepascal.org/Lazarus_Tdbf_Tutorial.
There are some limitations for DBF, Paradox and FoxPro db.

You need to install DBFLaz package from your Lazarus installation.

From Data Access pallete put into Form TDBF and Datasource components.
Set the FilePath property of TDBF. Choose the TDBF in DataSet property
from DataSource. Then from Data Control pallete put into Form for
example TDBGrid compenent and set it DataSource property.

I recommend your to convert your single user databases to something
modern, for example SQLite or Firebird embeded.

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Zvoni · 2020-06-23 10:15

Quote from: mig-31 on June 22, 2020, 06:32:37 pmI recommend to your to
convert your single user databases to something modern, for example
SQLite or Firebird embeded.
Seconded for SQLite!
In case you need to "save/transfer" existing live-data, IIRC, you can
open/import DBase-Files in Excel, then export it from there into CSV
or whatever.

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xinyiman · 2020-06-23 10:19

I advise you to convert your project to Firebird. So in addition to
using the SQL engine, you can make that data available to other
clients in the future.

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Handoko · 2020-06-23 10:48

Using Lazarus to connect dbf tables is super easy, I ever wrote some
programs using Lazarus - dbf. But just like others suggest, you should
consider other better alternatives. Quick and easy, use dbf but for
long time investment use the others.

Database video tutorials:
https://wiki.freepascal.org/Lazarus_videos#Database

How to load dbf data (to a string grid), try this example:
https://forum.lazarus.freepascal.org/index.php/topic,37181.msg249361.h
tml#msg249361

Lazarus-supported databases:
https://wiki.freepascal.org/Databases

Lazarus database portal:
https://wiki.freepascal.org/Portal:Databases

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wp · 2020-06-23 11:26

I agree with Handoko. Since you are new to Lazarus and want to convert
old Delphi programs you'll have to fight enough with the differences.
It does not make sense to change the database in the same step. So,
stick with TDbf to get started. Later, when the Laz-Delphi conversion
is done, you still can try to change the database.

For reading Paradox you have two options: either use TParadox which
comes with FPC (you must install the package
(lazarus)/components/paradox/lazparadox.lpk) or TParadoxDataset
(https://wiki.freepascal.org/TParadoxDataSet; install it via Online-
Package-Manager). I was more successful with the latter one since it
does not depend on any other library (unlike TParadox). Note, however,
that it is only good for reading!