InstantDBX

dbExpress broker for multiple database engines.

Overview

The InstantDBX unit provides database persistence using Borland's dbExpress (DBX) framework, a lightweight database access layer supporting multiple databases.

Supported Databases:

• Microsoft SQL Server
• MySQL
• InterBase/Firebird
• Oracle
• IBM DB2
• Informix
• PostgreSQL

Key Features:

• Lightweight dbExpress architecture
• High-performance unidirectional datasets
• SQL-based broker implementation
• Cross-database compatibility
• Transaction support

Note: dbExpress is a legacy framework. For new projects, use InstantFireDAC which provides better performance and modern features.

Key Classes

TInstantDBXConnectionDef

Connection definition for DBX broker.

Properties

Property	Type	Description
ConnectionName	string	DBX connection name from dbxconnections.ini
DriverName	string	DBX driver name (MSSQL, MySQL, IB, Oracle, etc.)
GetDriverFunc	string	Driver function name
LibraryName	string	Driver library filename
VendorLib	string	Vendor-specific library filename
Params	TStrings	Additional connection parameters

TInstantDBXConnector

Main connector component for dbExpress.

Inheritance:

TComponent → TInstantConnector → TInstantConnectionBasedConnector → TInstantDBXConnector

Properties

Property	Type	Description
Connection	TSQLConnection	dbExpress connection component
OnLogin	TSQLConnectionLoginEvent	Custom login handler

TInstantDBXBroker

SQL broker for dbExpress.

Inheritance:

TInstantBroker → TInstantSQLBroker → TInstantDBXBroker

Usage Patterns

Basic Setup - SQL Server

uses
  InstantDBX, Data.DBXCommon, Data.SqlExpr;

var
  Connection: TSQLConnection;
  Connector: TInstantDBXConnector;
begin
  Connection := TSQLConnection.Create(nil);
  Connection.DriverName := 'MSSQL';
  Connection.Params.Values['Database'] := 'MyDatabase';
  Connection.Params.Values['HostName'] := 'localhost';
  Connection.Params.Values['User_Name'] := 'sa';
  Connection.Params.Values['Password'] := 'mypass';

  Connector := TInstantDBXConnector.Create(nil);
  Connector.Connection := Connection;
  Connector.IsDefault := True;
  Connector.Connected := True;
end;

Basic Setup - MySQL

Connection.DriverName := 'MySQL';
Connection.Params.Values['Database'] := 'mydb';
Connection.Params.Values['HostName'] := 'localhost';
Connection.Params.Values['User_Name'] := 'root';
Connection.Params.Values['Password'] := 'mypass';

Basic Setup - Firebird

Connection.DriverName := 'Interbase';
Connection.Params.Values['Database'] := 'C:\Data\MyDatabase.fdb';
Connection.Params.Values['User_Name'] := 'SYSDBA';
Connection.Params.Values['Password'] := 'masterkey';
Connection.Params.Values['SQLDialect'] := '3';

Best Practices

1. Use Connection Names

// Define connection in dbxconnections.ini
Connection.ConnectionName := 'MyDBConnection';
Connection.LoadParamsFromIniFile;

2. Set Driver Properties

Connection.Params.Values['DriverUnit'] := 'Data.DBXMySql';
Connection.Params.Values['DriverPackageLoader'] := 'TDBXDynalinkDriverLoader';

3. Enable Transaction Support

if Connector.CanTransaction then
begin
  Connector.StartTransaction;
  try
    // Operations
    Connector.CommitTransaction;
  except
    Connector.RollbackTransaction;
    raise;
  end;
end;

Limitations

1. Legacy Framework: dbExpress is deprecated in favor of FireDAC
2. Unidirectional: Datasets are unidirectional by default
3. Limited Features: Fewer features than modern frameworks
4. Configuration Complexity: Requires driver configuration

Migration to FireDAC

Recommended migration path for new projects:

// Old (dbExpress)
uses InstantDBX;
Connector := TInstantDBXConnector.Create(nil);

// New (FireDAC - recommended)
uses InstantFireDAC;
Connector := TInstantFireDACConnector.Create(nil);

See Also

• InstantFireDAC - Recommended replacement
• InstantBrokers - Broker architecture
• InstantPersistence - Persistence infrastructure

Source Code

File: InstantDBX.pasLocation: Source/Brokers/DBX/

Summary

The InstantDBX broker provides database persistence using dbExpress, a lightweight cross-database framework.

Status: Legacy - Use InstantFireDAC for new projects.

Best for:

• Legacy applications using dbExpress
• Migration scenarios

Not recommended for:

• New projects (use FireDAC instead)