ACC95: Overview of Conversion Issues

• Microsoft Access version 7.0

SUMMARY

Moderate: Requires basic macro, coding, and interoperability skills.

Microsoft Access for Windows 95 version 7.0 has many enhancements, such as 32-bit architecture, Visual Basic for Applications, the Microsoft Jet data base engine version 3.0, and a modified data access objects (DAO) model. To take full advantage of these features, you should convert your databases created in an earlier version of Microsoft Access to Microsoft Access version 7.0.

Most Microsoft Access version 2.0 (or 1.x) databases can convert to version 7.0 without difficulty. In rare cases, however, new features can conflict with existing objects and code. This article discusses the following few issues that you may encounter when converting a database to version 7.0:

• Code Cannot Compile
• Conversion Process is Slow
• 16-bit API Calls Do Not Convert
• Custom Controls Do Not Convert
• Table Exceeds Limit of 32 Indexes
• Name Conflict Stops Conversion

MORE INFORMATION

Code Cannot Compile

When you convert a database to version 7.0, the conversion utility converts Access Basic code to Visual Basic for Applications and compiles the updated code. If any code does not successfully compile, you may receive the following error message after you convert a database to version 7.0:

   There were compilation errors during the conversion or enabling of
   this database.

   This database has not been saved in a compiled state. The performance
   of this database will be impaired because Microsoft Access will need to
   recompile the database for each session. For information on improving
   performance, click Help.

NOTE: In rare instances, the conversion utility may fail to convert some syntax. For example, it may fail to modify a DoCmd statement, such as the following,

   DoCmd OpenForm "MyForm"

   DoCmd.OpenForm "MyForm"

Conversion Process Is Slow

If you have a large database, the conversion process may take a long time or your computer may appear to stop responding (hang). The more objects that you have, the longer it takes to update the code and objects to version 7.0.

To speed the conversion process, try using the Import command instead of the Convert Database command by following these steps:

1. Create a new Microsoft Access version 7.0 database.

2. On the File menu, click Get External Data, and then click Import.

3. In the Import dialog box, make sure Microsoft Access (.mdb) is selected in the Files Of Type box.

4. Click the arrow to the right of the Look In box, select the drive and folder (directory) where the Microsoft Access database (.mdb) you want to import is located, and then double-click the database's icon.

5. Click 20 or so objects to import.

6. Click OK to import the selected objects.

7. Repeat steps 2-6 until all the objects are imported into the new database. Note that Microsoft Access converts the object to the new version 7.0 format as it is imported.

16-bit API Calls Do Not Convert

If your modules contain 16-bit API calls, you may receive the following error message when you convert the database to version 7.0:

   There are calls to 16-bit dynamic-link libraries (.dll) in modules
   in this database. These won't work under Microsoft Windows 95
   or Microsoft Windows NT.

Custom Controls Do Not Convert

When you convert to version 7.0, you may receive the following error message if your database contains an OLE custom control:

   One or more forms or reports contains a 16-bit OLE Custom Control
   with no 32-bit equivalent. These controls will not function
   properly under Microsoft Windows 95 or Microsoft Windows NT.

For more information about converting OLE custom controls, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q138019
   TITLE     : 16-bit OLE Controls Not Supported in Version 7.0

Table Exceeds Limit of 32 Indexes

If your database contains a table with 32 or more indexes and relationships combined, you may receive the following error message when you convert to version 7.0:

   Operation failed. There are too many indexes on table '<table name>'.
   Delete some of the indexes on the table and try the operation again.

To resolve this error, open your database in version 2.0 (or 1.x) and modify your table design to reduce the number of relationships for the primary key table or remove some indexes from the foreign key table. Then, you can try to convert the database to version 7.0.

This resolution assumes that you have version 2.0 (or 1.x) installed on your computer, as well as version 7.0. If you replaced version 2.0 (or 1.x) with version 7.0 using the same folder (directory) on your computer, then you must re-install version 2.0 (or 1.x). You may want to re-install into a different folder so that you have both versions available for resolving the conversion problem.

Name Conflict Stops Conversion

If a module has the same name as a type library, such as "DAO", "VBA", or "Access," the conversion process stops and Microsoft Access displays the following error message:

   Name conflicts with existing module, project, or object library.

This resolution assumes that you have version 2.0 (or 1.x) installed on your computer as well as version 7.0. If you replaced version 2.0 (or 1.x) with version 7.0 using the same folder on your computer, then you must re- install version 2.0 (or 1.x). You may want to re-install into a different folder so that you have both versions available for resolving the conversion problem.

REFERENCES