Step Next (24)
The Step Next operation (B_STEP_NEXT) retrieves the record to which the next physical position points. The transactional interface does not use a key path to retrieve the record.
A Step Next operation issued immediately after any Get or Step operation returns the record physically following the record retrieved by the previous operation.
Parameters
Op Code
Pos Block
Data Buf
Data Buf Len
Key Buffer
Key Number
Sent
Returned
Prerequisites
The file must be open.
Procedure
1
Set the Operation Code to 24. 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
.
2
Pass the Position Block for the file.
3
Set the Data Buffer Length to a value greater than or equal to the length of the record to retrieve.
Result
If the Step Next operation is successful, the transactional interface returns the file’s next physical record in the Data Buffer and sets the Data Buffer Length parameter to the number of bytes returned.
If the Step Next operation is unsuccessful, the transactional interface returns one of the following status codes:
3
The file is not open.
9
The operation encountered the end-of-file.
22
The data buffer parameter is too short.
Positioning
The Step Next operation does not establish logical currency. Step Next sets the physical currency using the retrieved record as the physical current record.
If a Step Next operation is issued immediately following a Delete operation (4), Step Next returns the record that was established as the next physical record by the operation
preceding
the Delete.
If a Step Next operation is issued immediately after an Open operation (0), Step Next returns the first record in the file.