Enform Plus Reference Manual

Links and the LINK OPTIONAL Statement Rules
Enform Plus Reference Manual—422684-001
C-11
Comparison of the LINK Statement, the LINK
OPTIONAL Statement, and the WHERE Clause
The LINK OPTIONAL statements establish the only links for this query. Although the
SUPPRESS clause contains a WHERE phrase, this WHERE phrase does not establish a
link. (If the WHERE phrase did establish a link, the links in this query would be invalid.)
Comparison of the LINK Statement, the LINK
OPTIONAL Statement, and the WHERE Clause
Table C-1 is 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 not
important 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 data from the data file
associated with the record
description name on the left side.
False True False