UniBasic Commands Reference - Rocket Software

READFWDU
Syntax
READFWDU dyn.array.var [FROM file.var] [ON ERROR statements]
[LOCKED statements] {THEN statements [END] | ELSE statements [END]}
READFWDU dyn.array.var [FROM file.var] [LOCKED statements]
[ON ERROR statements] {THEN statements [END] | ELSE statements [END]}
Description
The first READFWDU command retrieves the alternate key set by SETINDEX, and
then each subsequent READFWDU retrieves the next alternate key value in the
index. UniData reads the corresponding record into a dynamic array, and then assigns
the record ID to the @ID variable. READFWDU checks for locks. If the record is
available, READFWDU sets an exclusive (U) lock before reading the record.
Note: UniBasic locks are advisory only. For more information, see Developing
UniBasic Applications.
Using this command in a loop, a UniBasic program retrieves records in ascending
order based on an indexed attribute.
Before executing READFWDU, you must set a pointer to the alternate key value
with the SETINDEX command.
READFWDU sets the STATUS function return value to 10 if UniBasic detects a
duplicate alternate index key value and you have executed the ECL command
DUP.STATUS ON during the current work session.
READFWDU 1-617