UniBasic Commands Reference - Rocket Software

Parameters
The following table describes each parameter of the syntax.
Parameter Description
var Specifies the variable to contain the attribute.
FROM file.var, Specifies the file from which to read the attribute.
If you do not specify a file with file.var, the data is read from the
most recently opened default file.
record.ID.expr Specifies a record from which to read an attribute.
If you do not specify a file.var, UniData reads from the default
file. If no default file is open, a fatal error occurs.
The default file is one for which no file variable is assigned in
the OPEN statement.
attribute.expr Specifies an attribute from which to read.
ON ERROR statements Specifies statements to execute if the READVL statement fails
with a fatal error because the file is not open, an I/O error occurs,
or UniData cannot find the file.
If you do not specify the ON ERROR clause and a fatal error
occurs, the program terminates.
LOCKED statements Specifies statements to execute if the record is locked by another
user. If you do not specify a LOCKED clause, the program waits
until the lock on the record is released.
Use the ECL command DEFAULT.LOCKED.ACTION BELL
to make the terminal beep while you wait for UniData to unlock
the record.
THEN statements END THEN executes if the read is successful. END is required to
terminate multiline THEN statements.
ELSE statements END ELSE executes if the read is not successful or the record (or ID)
does not exist. END is required to terminate multiline ELSE
statements.
READVL Parameters
READVL 1-651