Databases

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Work in progress..

Introduction

This page will be an entrance to the topic 'Lazarus and databases'. The following table provides an overview about the supported databases. It needs to be updated soon, because it is based on the time when FPC 1.9.7 was released. Warning: You should only install the database components for which you have the client libraries installed (if the database need client libaries). Otherwise Lazarus could fail to start because of missing files. You would then have no choice but to reinstall Lazarus, because uninstalling the component isn't possible.

Table 1

Database Package name Need client lib? Need server? Supported versions Supported platforms
Textfiles sdf No No - All
In memory memds No No - All
DBase DBFLaz No No III+, IV, VII All
FoxPro DBFLaz No No - All
Paradox TParadoxDataSet No No up to Table Level 7 (and up ??) All
SQLite SQLite Yes No - -
MySQL SQLdb Yes Yes 3 - 4.0 i386: Linux, Win32
Firebird IBase Yes Yes 1 - 1.5 i386: Linux, Win32
PostgreSQL SQLdb Yes Yes 6.6 - 8 i386: Linux, Win32
ODBC SQLdb Yes Depends 3.x 1) i386: Linux, Win32
Interbase IBase Yes Yes 4 - 6 i386: Linux, Win32
Oracle SQLdb Yes Yes - -

1) This version number refers to the ODBC standard, not to the version number of a driver or driver manager. There are ODBC 3.x drivers for most DBMSs.

The bindings to the database-clients

If you want to use one of the databases-client libraries, those libraries have to be installed. Not only on the computer you're programming on, but also on the computers where the application must run. Note that some databases (in particular MySQL) only work if the bindings which are compiled in the application are from the same version as those of the installed libraries. You can find out how to install those libraries (.so files on *nix systems, and .dll's on windows) on the website of the database-developers. The binding units can be found in the packages/base directory in the fpc-sources. They basically consist of the client-api calls like mysql_connect_database, which are completely different for each database. It is possible to write database applications using these units, but it is usually far more work and bug-sensitive than using the DB-unit Lazarus components.

Most of these bindings-packages are hard-linked to the client-libraries. This means that if the application is compiled with one of these units in it, the whole application can not be linked if the client libraries are not available on the workstation. This means that if you do not have installed - for example - MySQL on your computer, and you are using the mysql4.pp unit in your program. The program will not link. If you succeed to compile the program on a computer which has MySQL installed, it still won't even start on any other workstation without the appropriate MySQL-libraries.

To avoid such problems some of the packages are also able to link dynamically to the libraries. Before any calls to those libraries can be made, the unit has to be 'initialized'. This initialization fails if the database-client isn't installed on the computer. If the program is ready using the client-library, the unit has to be 'released'.

Additional information about Lazarus and databases

Database packages contained in Lazarus

sqldblaz.lpk

This package provides access to different databases (e.g. MySQL or Interbase/Firebird). The components (TSQLQuery, TSQLTransaction, TIBConnection, TODBCConnection, TOracleConnection, TMySQL40Connection, TMySQL41Connection, TMySQL50Connection, TPQConnection) are on the 'SQLdb' tab in the component palette.

dbflaz.lpk

This package provides access to dBase and FoxPro databases. You can get more information in the Lazarus Tdbf Tutorial. The TDbf component is on the 'Data Access' tab in the component palette.

sqlitelaz.lpk

This package provides access to SQLite databases. You can get more information in the Lazarus Database Tutorial.

sdflaz.lpk

The component TSdfDataSet can be found on the 'Data Access' tab in the component palette.

lazreport.lpk

The homepage of the report generator is http://lazreport.sourceforge.net/. More informationen (et al. an additional link) can be found here. LazReport depends on the Printer4Lazarus package. With revision 11950 LazReport was included in the Lazarus SVN repository.

External packages / libraries

Zeos DataBase Objects

These components provide access to different databases. You can find more information here. This wiki also contains a Zeos tutorial.

Pascal Data Objects

There is now an alternative. The functions introduced with MySQL 4.1 and 5.0 like prepared statements, binding, and stored procedures are supported by database API called Pascal Data Objects, which is inspired by PHP Data Objects. All the code and documentation necessary to use this new API is available on Sourceforge:

http://pdo.sourceforge.net

Jan 30, 2007: PDO has added drivers for Firebird 1.5 and Firebird 2.0

TPSQL

These components provide access via TCP/IP to PostgreSQL databases. You can find more information on this page.

FIBL

These components provide access to Interbase and Firebird databases. The homepage is http://sourceforge.net/projects/fibl.

FBLib Firebird Library

FBLib is an open Source Library No Data Aware for direct access to Firebird Relational Database from Borland Delphi/Kylix, Free Pascal and Lazarus.

Current Features include:

  • Direct Access to Firebird 1.0.x, 1.5.x and 2.x Classic or SuperServer
  • Multiplatform [Win32,Gnu/Linux,FreeBSD)
  • Automatic select client library 'fbclient' or 'gds32'
  • Query with params
  • Support SQL Dialect 1/3
  • LGPL License agreement
  • Extract Metadata
  • Simple Script Parser
  • Only 100-150 KB added into final EXE
  • Support BLOB Fields
  • Export Data to HTML SQL Script
  • Service manager (backup,restore,gfix...)
  • Events Alerter

You can download documentation on FBLib's website.

Unified Interbase

UIB provides access to Interbase, Firebird and YAFFIL databases. The homepage is www.progdigy.com. A svn repository is available under https://uib.svn.sourceforge.net/svnroot/uib .

TechInsite Object Persistence Framework (tiOPF)

More information about tiOPF can be found on this page.