E@DBFINDPRV
Name
The E@DBFINDPRV call has the following format:
DN@<Logical>(E@DBFINDPRV)
where <Logical> identifies the database file and index to use to perform the E@DBFINDPRV call.
Description
Once you have defined a position in the file with a successful E@DBFINDGE, use the E@DBFINDPRV routine to process database records sequentially in reverse <Index> order. This routine reads the record preceding the current record for this index.
Using the API in a Program
You must precede E@DBFINDPRV with E@DBFINDGE.
E@DBFINDNXT and E@DBFINDPRV each require their own E@DBFINDGE calls to function properly; do not use together after a single E@DBFINDGE call.
Input Values
| Field | Description |
|---|---|
| <Logical> | <Logical> identifies the database file and index to use to perform the call. |
Return Values
| Field | Description |
|---|---|
| D<prefix>@NOTFOUND |
Each routine sets the logical value <FileName>-NOTFOUND or <FileName>-FOUND based on the outcome of the read process. The Find routines set D<prefix>@NOTFOUND to FALSE if a record is found, TRUE if a record is not found, or E@KEY@FOUND if the keys are found. |
Programming Example
This example shows a way to move backward and forward in a file depending on the action being processed. In this example, the index key to be used is set, the action code is checked, and the routine gets either the next record or the previous record.
Notice that the E@DBFINDGE call is made separately for each type of action code.
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