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PROBLEM:
I have a Microsoft Access table and use ODBC Connectivity Kit to use it in my applications. The table has an autonumber ID -- and that is the identity column. I am saving a new record and doing a reread on that table. The reread fails -- it says that the record could not be found...
What could that be?
SOLUTION:
Since Visual DataFlex 11 and Connectivity Kit 4, there has been two programming styles that can be used to handle tables in the Application framework: RowId and RECNUM style.
Some of the differences between these styles are:
- There is no explicit recnum column in a standard table. A standard table will not have a column 0.
- Because there is no recnum column, you cannot move a value to it. This means that all of the RECNUM "tricks" such as moving 0 recnum to inactivate a buffer cannot be used.
- A standard table will not expose a recnum index (i.e., no index.0).
- Attempts to use recnum or index.0 in a standard table will result in an error.
When using standard tables, the RECNUM style cannot be used; RowId style is mandatory. When using recnum tables, both RECNUM- and RowId styles can be used.
In this case, your table is probably set to be standard -- that's the default the connection wizard uses. Check the INT file for that table; the RECNUM_TABLE keyword is probably set to NO.
If you keep that keyword set to NO, you will need to use RowID in your programs. If you want to program using RECNUM style, you will need first to make sure the ID in your table fulfill the API requirements:
The API requires every recnum table it accesses to have a record number like column called the record identity. This column can be a logical column or actually exist in the table and it should have the following characteristics:
- Uniquely identify a row
- Be numeric with no decimal places
- Range from 1 to 2^31 (2147483647)
- Be available as a unique index
If it does, you can change the RECNUM_TABLE keyword to YES and your program should work as expected. If it does not, you will need to use RowID in your programs.
Contributed By:
Marcia Booth
Company: Data Access Worldwide
Web Site: http://www.dataaccess.com
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