ENFORM User's Guide

Connecting Record Descriptions to Form New Relationships
Developing an ENFORM Query
058058 Tandem Computers Incorporated 3–15
ENFORM converts the preceding WHERE clause into two “terms”:
> first term
> second term
empnum < 100 AND
regname = "GERMANY"
Notice that ENFORM produces a target record from the logical record occurrence
whose empnum value is 49. ENFORM does not use the second “term” (regname =
“GERMANY”) to evaluate this logical record occurrence because the region record
description is “non-contributing” for this logical record occurrence. (This record
description is “non-contributing” because the regnum value (7) in the contributing
employee record occurrence does not match a regnum value in the region record
occurrences.)
Clearing Unnecessary Session-Wide Links
You can clear unnecessary session-wide links (links created by either the LINK
statement or the LINK OPTIONAL statement) by using one of the following:
A CLOSE statement which clears all links referencing the record descriptions
being closed.
A DELINK statement which clears the specified link.
Either a DICTIONARY statement or a ?DICTIONARY command that clears the
entire internal table.
Unnecessary links take up memory space, produce undesirable results in subsequent
queries, and might lengthen processing time. After clearing unnecessary links, you
can use the ?SHOW link command to verify the removal of the links.
Examining Session-Wide Links
You use the ?SHOW link command to examine session wide links. For example, if you
enter:
LINK parts TO fromsup VIA partnum;
LINK employee TO OPTIONAL region VIA regnum;
and later enter a ?SHOW LINK command, ENFORM displays:
PARTS.PARTNUM is linked to FROMSUP.PARTNUM
EMPLOYEE.REGNUM is linked optional to REGION.REGNUM