Article #25188: Handling BDE Engine Errors

Problem:
A Delphi or C++ Builder generated application produces a BDE Engine exception.
Solution:
An exception was produced in the Delphi generated application due to an error
from the RDBMS server (i.e InterBase), the BDE or an ODBC driver.
Using the Borland BDE Configuration Utility (BDECFG.EXE, or BDEADMIN.EXE)
to examine the SQLQRYMODE property of the InterBase or Visigneic ODBC alias
being used in the application. If the setting is  or set to LOCAL change the
setting to SERVER. Save the changes and exit the utility.
If the application is using a TDatabase component, bring the application up in
Delphi and left double-click the mouse on the TDatabase component to bring
up the Database Login dialog. Change the SQLQRYMODE property in the
parameters list box to SERVER, if the property is present. Save and do a Build All.
At this point exiting the Delphi IDE and starting it again may be required so that
the new changes in the BDE aliases will be re-read and accounted for.
SQLQRYMODE Settings
========================================
: The BDE sends the SQL query string to the RDBMS server or the ODBC data
source and if an error is returned the BDE will then parse the string itself and
will send the parsed string (or strings) to the server.
LOCAL: The BDE will parse the strings and send the parsed string (or strings) to the
server.
SERVER: The BDE will send the SQL query string to the RDBMS SERVER or the
ODBC datasource. If an error occurs then this will be returned through
the BDE.
By changing the setting to SERVER the error returned will be in direct relation
to the SQL query that was requested by the Delphi application. Next, run the
application and try to reproduce the exception.
When the exception is reproduced the BDE will take the resulting error
from the server and will map it through one of its existing error codes
and messages. If the error is "General SQL Error: " this indicates
that an error occurred on the server and the BDE did not have a comparable
or corresponding error message to map it to so it returned this error. The
 portion will be the error string that is returned from the server
(or ODBC datasource). This is the easy case, match the error string with
the errors listed in the InterBase Language Reference, or with a listing of
ODBC errors.
If another error is produced then it is uncertain if the error is from the server,
the BDE, or an ODBC driver, this is the not-so-easy case. Delphi provides a
way to look at where the error is coming from, follow the instructions in the
following paragraphs.
To further track down the source of the exception start by placing a memo
on the main form. This memo will be used to display further information
that is available in the BDE Engine Exception object. Next implement the
following code snippet into the main form of the application:
unit dbughelp;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls, DB;
type
TForm1 = class(TForm)
Memo1: TMemo;
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
procedure MyHandler(Sender: TObject; E:Exception);
end;
var
Form1: TForm1;
implementation
{$R *.DFM}
procedure TForm1.FormCreate(Sender: TObject);
begin
Application.OnException := MyHandler;
end;
procedure TForm1.MyHandler(Sender: TObject; E: Exception);
var
i: Word;
F: EBDEEngineError;
begin
Memo1.Lines.Add('== Begin Entries for Exceptions ==');
Memo1.Lines.Add(E.ClassName);
if (E is EBDEEngineError) then begin
F := EBDEEngineError(E);
Memo1.Lines.Add('ErrorCount = ' + IntToStr(F.ErrorCount));
for i := 0 to F.ErrorCount — 1 do begin
Memo1.Lines.Add(' ');
Memo1.Lines.Add('----------');
Memo1.Lines.Add(' ');
Memo1.Lines.Add('NativeError = ' + IntToStr(F.Errors[i].NativeError));
Memo1.Lines.Add('Message = ' + F.Errors[i].Message);
Memo1.Lines.Add('ErrorCode = ' + IntToStr(F.Errors[i].ErrorCode));
end;
end;
Memo1.Lines.Add('== End Entries for Exceptions ==');
end;
end.
In the FormCreate procedure (i.e OnCreate event) the application global
exception handler is re-routed to a custom exception handler, the Myhandler
procedure. Within the MyHandler procedure the error information in the BDE
Engine Exception object is placed in the memo component. After the BDE
Engine Exception information is placed in the memo look for the NativeError
codes. The errors will follow a specific pattern for InterBase , the BDE and for
ODBC. The patterns of the error messages are:
InterBase: The errors will follow the pattern of -xxx, like a -902 error.
Use the InterBase Language Reference manual to look up the error and the
error message.
BDE: Download the DBI Error checking utility from the BDE Technical Support
pages of the www.borland.com website. Run the utility and type in the
error number, the corresponding error message will be returned.
ODBC: Try consulting an ODBC reference for the error code.

Last Modified: 29-SEP-00