Get Greater Than or Equal (9)
The Get Greater Than or Equal operation (B_GET_GE) retrieves a record in which the value for the key specified by the Key Number is equal to or greater than the value you supply in the Key Buffer. The transactional interface first tries to satisfy the equal requirement. If the key allows duplicates, this operation retrieves the first record (chronologically) of the group with the same key values. 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.
Note:
If you are using the Get Greater Than or Equal operation on descending keys, the next greater value refers to a value lower than the one specified in the Key Buffer.
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
1
Set the Operation Code to 9. 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 you want to retrieve.
4
Specify the key value in the Key Buffer parameter.
5
Set the Key Number parameter to correspond to the correct key path. To use the system-defined log key (also called system data), specify 125.
Result
If the Get Greater Than or Equal operation is successful, the transactional interface stores the record in the Data Buffer, the key value in the Key Buffer, and the length of the record in the Data Buffer Length parameter.
If the Get Greater Than or Equal 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.
22
The data buffer parameter is too short.
Positioning
The Get Greater Than or Equal operation establishes the complete logical and physical currencies and makes the retrieved record the current one.
Note: If you are using the Get Greater Than or Equal operation on descending keys, the next greater value refers to a value lower than the one specified in the Key Buffer.