Databases - Delphi - Connecting to a Firebird (Interbase) Database

Firebird is an open source (free) version of Borland's Interbase SQL database engine. There are Several different ways to access tables

ODBC/ADO
Interbase components
dbExpress

According to Borland, there will not be any further changes to the BDE (Borland Database Engine), as a result, it should not be used in new designs.

ODBC

So far, I have not gotten ODBC to work using an Interbase ODBC driver with the Firebird Server.

In order to access an *.gdb (or *.fdb) file,

Add these components - KADaoDatabase, KADaoTable, DataSource, DBGrid
Set KADaoTable1.Database to KADaoDatabase1
Set DataSource1.DataSet to KADaoTable1
Set DBGrid1.DataSource to DataSource1

I got lots of errors related to the Workgroup information file, but, of course, there is no help on what that may mean.

KADaoDatabase1.UserName	sysdba
KADaoDatabase1.Password	masterkey
KADaoDatabase1.DatabaseType	ODBC
KADaoDatabase1.Database	Select from the list of ODBC or BDE database aliases. (I am assuming that your system has at least one defined.) Setting this clears Database1.DatabaseName.
KADaoDatabase1.DatabaseName	This is the name that TTable components will link to. This can be the same as Database1.AliasName, you may make up a name, or you may enter the fully qualified path to a Paradox database (directory). An MS Access mdb file can not be entered here.
KADaoDatabase1.LoginPrompt	Set this False to disable the default dialog box.
KADaoDatabase1.OnLogin	Attaching code to this event will also disable the default dialog box. (Hardcoding userID's and passwords is considered to be a security problem.)

Using the Interbase Components

In order to access an *.gdb file,

Add these components - IBDatabase, IBTransaction, IBTable, DataSource, DBGrid

IBDatabase1.DatabaseName	Set this to the .gdb or .fdb file
IBDatabase1.Connected	Set to true
IBTransaction1.DefaultDatabase	Set to IBDatabase1
IBTransaction1.DefaultAction	Set to TACommit
IBTransaction1.Active	Set to true
IBTable1.Database	Set to IBDatabase1
IBTable1.Transaction	Set to IBTransaction1
IBTable1.TableName	Select a table from the list.
IBTable1.Active	Set to true
DataSource1.DataSet	Set to IBTable1
DBGrid1.DataSource	Set to DataSource1

Be sure not to set IBTable1.MasterSource to DataSource1 - if you do, you get the following error

Circular datalinks are not allowed.

Instead of IBTable, you can use IBDataSet and set SelectSQL to

select * from CUSTOMER

Or you can use IBClientDataSet and set CommandText to the query.

dbExpress

dbExpress is Borland's new way to connect to SQL databases - supposedly, only one additional *.dll (dbexpint.dll) is required on the client systems in order to connect to an Interbase/Firebird database. (Well, that's what the documentation says.)

(dbExpress is available with Delphi 6 Pro and Delphi 7 Pro, but not with Delphi 5 Pro.)

The first problem is that dbExpress produces a link to a "unidirectional" database - this causes the DataGrid to not work. The solution with Delphi 6 was to use a TClientDataSet which buffers data in memory so that bidirectional access is simulated.

It turns out that Delphi 7 requires an additional TProvider component.

It was also not clear from the documentation how to configure the TClientDataSet. The solution is to set xx to one of these - table, query, storedProc - and to set xx to an appropriate value.

Well, I eventually got this to work. Then I tried to get the *.exe to run on a machine that did not have Delphi 7 installed.

I never got it to work on another Windows 98 system
On Windows XP, I had to supply the following *.dll's - luckily, the error boxes told me what was missing.

Notice - Delphi 6 does not require the xxx component. That means that code written for Delphi 6 must be modified before it will compile with Delphi 7.

Author: Robert Clemenzi - clemenzi@cpcug.org