Get Last (13)

The Get Last operation (B_GET_LAST) retrieves the logical last record based on the specified key. If duplicates exist for the last key value, the record returned is the last duplicate. You can use the Get Key (+50) bias to detect the presence of a value in a file. A Get Key operation is generally faster.

Parameters


	Op Code	Pos Block	Data Buf	Data Buf Len	Key Buffer	Key Number
Sent
Returned

Prerequisites

The file must be open.

The file cannot be a data-only file.

Procedure

Set the Operation Code to 13. Optionally, you can include a lock bias:

+100-Single wait record lock.

+200-Single no-wait record lock.

+300-Multiple wait record lock.

+400-Multiple no-wait record lock.

For more information about locking, refer to the Pervasive PSQL Programmer's Guide.

Pass the Position Block for the file.

Set the Data Buffer Length to a value greater than or equal to the length of the record you want to retrieve.

Specify the Key Number for the key path. To use the system-defined log key (also called system data), specify 125.

Result

If the Get Last operation is successful, the transactional interface returns the requested record in the Data Buffer, stores the corresponding key value in the Key Buffer, and returns the length of the record in the Data Buffer Length parameter.

If the Get Last operation is unsuccessful, the transactional interface returns one of the following status codes:


3	The file is not open.
6	The key number parameter is invalid.
9	The operation encountered the end-of-file.
22	The data buffer parameter is too short.

Positioning

The Get Last operation establishes the complete logical and physical currencies and makes the retrieved record the current one. The logical next position points beyond the end of the file.