Technical data

• For the NULL condition, the referenced currency indicator points to a vacant
position in the database or collection:
Realm currency indicator (DB-CONDITION is set to DBM$_CRELM_
POS).
Set currency indicator (DB-CONDITION is set to DBM$_CSTYP_POS).
Run-unit currency indicator (DB-CONDITION is set to DBM$_CRUN_
POS).
See the USE statement for more information on USE FOR DB-EXCEPTION.
4.5.4 Condition Evaluation Rules
Parentheses can specify the evaluation order in complex conditions. Conditions in
parentheses are evaluated first. In nested parentheses, evaluation starts with the
innermost set of parentheses. It proceeds to the outermost set.
Conditions are evaluated in a hierarchical order when there are no parentheses
in a complex condition. This same order applies when all sets of parentheses are
at the same level (none are nested). The hierarchy is shown in the following list:
1. Values for arithmetic expressions
2. Truth values for simple conditions, in this order:
a. Relation
b. Class
c. Condition-name
d. Switch-status
e. Sign
f. Database
g. Success/failure
3. Truth values for negated simple conditions
4. Truth values for combined conditions, in this order:
a. AND logical operators
b. OR logical operators
5. Truth values for negated combined conditions
In the absence of parentheses, the order of evaluation of consecutive operations at
the same hierarchical level is from left to right.
4.6 Record Selection Expressions (RSE)
A record selection expression is used to select a record in the database. It can
be used in a FETCH or FIND statement. The record thus selected becomes the
current record of the run unit upon which subsequent statements may operate
when accessing the database.
Refer also to the Oracle CODASYL DBMS Programming Guide and the Oracle
CODASYL DBMS Programming Reference Manual for additional information.
Procedure Division 4–9