Application Programming and SQL Guide - Kmlinux

|
|
|
|
v DEC31 rules allow a maximum precision of 31 digits in the result. DEC31 rules
are in effect if any of the following conditions is true:
– Either operand of the operation has a precision greater than 15 digits.
– The operation is in a dynamic SQL statement, and any of the following
conditions is true:
- The current value of special register CURRENT PRECISION is DEC31 or
D31.s. s is a number between one and nine and represents the minimum
scale to be used for division operations.
- The installation option for DECIMAL ARITHMETIC on panel DSNTIP4 is
DEC31, D31.s, or 31; the installation option for USE FOR
DYNAMICRULES on panel DSNTIP4 is YES; and the value of CURRENT
PRECISION has not been set by the application.
- The SQL statement has bind, define, or invoke behavior; the statement is in
an application precompiled with option DEC(31); the installation option for
USE FOR DYNAMICRULES on panel DSNTIP4 is NO; and the value of
CURRENT PRECISION has not been set by the application. See “Using
DYNAMICRULES to specify behavior of dynamic SQL statements” on page
487 for an explanation of bind, define, and invoke behavior.
– The operation is in an embedded (static) SQL statement that you precompiled
with the DEC(31), DEC31, or D31.s option, or with the default for that option
when the install option DECIMAL ARITHMETIC is DEC31 or 31. s is a number
between one and nine and represents the minimum scale to be used for
division operations. See “Step 1: Process SQL statements” on page 462 for
information about precompiling and for a list of all precompiler options.
Recommendation: Choose DEC31 or D31.s to reduce the chance of overflow, or
when dealing with a precision greater than 15 digits. s is a number between one
and nine and represents the minimum scale to be used for division operations.
Avoiding decimal arithmetic errors: For static SQL statements, the simplest way
to avoid a division error is to override DEC31 rules by specifying the precompiler
option DEC(15). In some cases you can avoid a division error by specifying D31.s.
This specification reduces the probability of errors for statements that are
embedded in the program. s is a number between one and nine and represents the
minimum scale to be used for division operations.
If the dynamic SQL statements have bind, define, or invoke behavior and the value
of the installation option for USE FOR DYNAMICRULES on panel DSNTIP4 is NO,
you can use the precompiler option DEC(15), DEC15, or D15.s to override DEC31
rules.
For a dynamic statement, or for a single static statement, use the scalar function
DECIMAL to specify values of the precision and scale for a result that causes no
errors.
Before you execute a dynamic statement, set the value of special register
CURRENT PRECISION to DEC15 or D15.s.
Even if you use DEC31 rules, multiplication operations can sometimes cause
overflow because the precision of the product is greater than 31. To avoid overflow
from multiplication of large numbers, use the MULTIPLY_ALT built-in function
instead of the multiplication operator.
Chapter 1. Retrieving data 17