UniBasic Commands Reference - Rocket Software

READFWDL
Syntax
READFWDL dyn.array.var [FROM file.var] [ON ERROR statements]
[LOCKED statements] {THEN statements [END] | ELSE statements [END]}
READFWDL dyn.array.var [FROM file.var] [LOCKED statements]
[ON ERROR statements] {THEN statements [END] | ELSE statements [END]}
Description
The first READFWDL command retrieves the alternate key set by SETINDEX, and
then each subsequent READFWDL 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. READFWDL checks for locks. If the record is
available, it sets a shared (L) lock.
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 READFWDL, you must set a pointer to an alternate key value with
the SETINDEX command. The SETINDEX parameters BUFFER.KEYS and
VALIDATE.KEY determine, respectively, whether the buffering mechanism is used
and whether keys are validated when READFWDL executes. For details, see
SETINDEX.
READFWDL 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.
READFWDL 1-613