question reg. MS-Access database access using VB3

question reg. MS-Access database access using VB3

Post by Sharada Technologies In » Wed, 08 May 1996 04:00:00



Hello,

i'm facing a particular problem accessing Access2.0 database in VB3.
i've an app which is setup on a machine which runs on win95, has 'office
for win95 (which includes Access7)', has the compatiblity layer (i don't
know whether this is required).

the app was distibuted by using the standard Setup wizard on a machine
which runs on win95, has vb3.0 + Access 2.0 + compatiblity layer.

The app when run reads/writes the database correctly, the problem arises
when i try to start a Crystal report from within the application. The error
given is 'Error detected by database DLL'.

Can anyone please help me with this problem?

TIA.

- Atul

 
 
 

question reg. MS-Access database access using VB3

Post by Jeremy Markm » Thu, 09 May 1996 04:00:00



: The app when run reads/writes the database correctly, the problem arises
: when i try to start a Crystal report from within the application. The error
: given is 'Error detected by database DLL'.

This error has nothing to do with the platform you are running on.  
Rather it has to do with the data.  Crystal Reports does not handle Null
values in data very well, and you can get this error if you are a field
used in a formula has a Null Value.
To workaround this you could do two things:
Make sure your VB code does not allow any Null values...i.e. replace all
Null's with empty strings...
or
use the IsNull({Table1.Field1}) function in your crystal formulas so that
you avoid trying to manipulate a field value that is Null...

 
 
 

question reg. MS-Access database access using VB3

Post by Steve DeGeorge, S » Fri, 10 May 1996 04:00:00


Quote:>the app was distibuted by using the standard Setup wizard on a machine
>which runs on win95, has vb3.0 + Access 2.0 + compatiblity layer.

>The app when run reads/writes the database correctly, the problem arises
>when i try to start a Crystal report from within the application. The error
>given is 'Error detected by database DLL'.

Crystal Reports also needs to be patch to use the Access 2.0 layer.

--
                                Steve DeGeorge SR      
                                Sharkware Computing

 
 
 

1. Regarding Accessing External database using MS-Access and MS-Visual Basic

Hi from Srinivas
I have a problem when I have an attached a table from an external
Database(foxpro version 2.6 for Dos,*.dbf) to Access 2.0 database.I am
using Visual Basic on Windows-95.
I need to Delete or Update records in the external Database(Attached
Table) and want to reflect those changes in the attached table (i.e in
Access) using Visual Basic.
There are two ways of doing it.
1) Use a Tabledef object(Visual Basic) to create a attached table in
Access and then carry out necessary actions like Delete or Update on the
External table. But this Tabledef is Readonly and not letting me to
Delete or Update the attached External table.

This is the help in VB about deleting records for a Externally attached
Foxpro Database.
Deleted Records:
In most cases, if you Delete a record when working with External data,
the record is actually removed from the source table.  When working with
FoxPro tables, however, Deleted records aren't actually removed until
the table is packed using FoxPro commands or utilities.  The Jet
engine's CompactDatabase method of the DBEngine object works only on Jet
Databases; it has no effect on Microsoft FoxPro Databases.
You can tell the Jet database engine not to include deleted records by
setting the Deleted parameter of the initialization settings to True.
If you set the Deleted parameter to False, all records are included in
any Recordset objects you create, even deleted records.

I tried this by setting the Deleted Parameter = true in the
MsAccess20.ini(in windows directory)
I then opened the Access database and checked the external table. But
still I dont have the most recent or refreshed view of the external
database.
This didnt work.

2) Use the OpenDatabase directly on the external database using the
Connect string and then open a Recordset and then carry out necessary
actions like Delete or Update on the External Table.
But still I dont have the most recent or refreshed view of the external
database.
It works only when I open the Foxpro Database (version 2.6 for Dos) and
Pack and Reindex it.
Could someone suggest me is there any other way to get around this
problem.Should the external Database opened in Exclusive mode for action
related Queries(Delete or Update)
Which is the better method using Tabledef method or OpenDatabase method.


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