Use an arithmetic expression to combine value expressions and
arithmetic operators. When you use an arithmetic expression in
a statement, Oracle Rdb calculates the value associated with the
expression and uses that value when executing the statement.
Therefore, an arithmetic expression must result in a value. If
either operand of an arithmetic expression is a missing value,
the resultant value also is a missing value.
1 – Examples
The following programs demonstrate the use of the multiplication
(*) arithmetic operator and the MODIFY statement. These programs
select the record of an employee in the SALARY_HISTORY relation
with a specified employee ID and that has no value for SALARY_
END. The purpose of specifying no value for SALARY_END is to
ensure that the only salary amount affected is the employee's
present salary. Next, the programs multiply the employee's
salary by 1.1 to produce an increase of ten percent in his or
her salary. The MODIFY statement replaces the old value in this
employee's SALARY_AMOUNT field with the new value.
1.1 – C Example
#include <stdio.h>
DATABASE PERS = FILENAME "PERSONNEL";
main()
{
READY PERS;
START_TRANSACTION READ_WRITE;
FOR SH IN SALARY_HISTORY
WITH SH.EMPLOYEE_ID = "00164"
AND SH.SALARY_END MISSING
MODIFY SH USING
SH.SALARY_AMOUNT = SH.SALARY_AMOUNT * 1.1;
END_MODIFY;
END_FOR;
ROLLBACK;
FINISH;
}
1.2 – Pascal Example
program multiply (input,output);
DATABASE PERS = FILENAME 'PERSONNEL';
begin
READY PERS;
START_TRANSACTION READ_WRITE;
FOR SH IN SALARY_HISTORY
WITH SH.EMPLOYEE_ID = '00164'
AND SH.SALARY_END MISSING
MODIFY SH USING
SH.SALARY_AMOUNT := SH.SALARY_AMOUNT * 1.1;
END_MODIFY;
END_FOR;
ROLLBACK;
FINISH;
end.
2 – Format
(B)0[marith-expr =
qwq> numeric-value qwqqwqq> + qqwqqwq> numeric-value qwqqq>
tq> numeric-host-var qu tqq> - qqu tq> numeric-host-var qu
mq> numeric-db-field qj tqq> * qqu mq> numeric-db-field qj
mqq> / qqj
2.1 – Format arguments
numeric-value A numeric literal.
numeric-host-var A host language variable that holds a
numeric value.
numeric-db-field A database field (qualified with a context
variable) that holds a numeric value.
+ - * / Arithmetic operators. The following table
lists the arithmetic operators and their
functions.
Operator Function
--------------------------
+ Add
- Subtract
* Multiply
/ Divide
--------------------------