5.4.Controlling ODBC Cursor Library Usage
The OpenLink ODBC Provider requires that the underlying ODBC driver supports some form of scrollable cursor. In order to support OLE DB rowsets, the minimum scrolling functionality requirements include:
| bookmark support |
| absolute cursor positioning |
| backwards scrolling |
Keyset driven and static cursors both support this functionality. All OpenLink ODBC drivers support these cursor models. However, if the OpenLink ODBC provider is to be used with a third party driver, either the driver must support one of these cursor types natively, or the Microsoft ODBC Cursor Library must be used. The latter only supports static scrollable cursors, but provides sufficient functionality to allow third party drivers to be used with the OpenLink provider. When using an OpenLink ODBC driver, it is preferable not to use the Microsoft Cursor Library.
To control how the OpenLink Provider uses the ODBC Cursor Library, the provider supports the provider specific keyword Cursors in the Extended Properties property string. The keyword can be set to one of three values:
| ODBC |
| Driver |
| IfNeeded |
The meaning of each of these values is analogous to their ODBC counterpart SQL_CUR_USE_xxx. The default setting is Cursors=IfNeeded.
The table below lists the required Cursors setting for various ODBC drivers when used with the OpenLink ODBC Provider.
Table5.1.Features Comparison
| ODBC Driver | Cursor | Comments |
|---|---|---|
| All OpenLink ODBC drivers | Driver or IfNeeded (default) | The native scrollable cursor support in the OpenLink drivers provides the necessary functionality |
| Native Microsoft SQL Server driver | ODBC | The native scrollable cursor support is inadequate. |