ENFORM Reference Manual

Comparison of the LINK Statement, the LINK OPTIONAL Statement, and the WHERE Clause
LINKS and the LINK OPTIONAL Statement Rules
C–12 058057 Tandem Computers Incorporated
Comparison of the LINK Statement, the LINK OPTIONAL Statement, and the WHERE Clause
Table C-1 contains a truth table that compares the LINK statement, the LINK
OPTIONAL statement, and the WHERE clause.
Table C-1. Truth Table
LINK
Statement
LINK OPTIONAL
Statement
WHERE
Clause
Establishes a session-wide link. True True False
Establishes a two-directional link. True False True
Can link more than two record
descriptions.
False False True
The order in which you specify record
description names is unimportant.
False True True sometimes
(The order is
unimportant if you
link record
descriptions by
specifying that their
linking field values
must be equal.)
Builds logical records from matching
records in the data files associated with
all linked record descriptions
True False True
Builds logical records by preserving the
data from the data file associated with
the record description name on the left
side.
False True False