Skip to Main Content
Oracle in a Nutshell
book

Oracle in a Nutshell

by Rick Greenwald, David C. Kreines
December 2002
Intermediate to advanced content levelIntermediate to advanced
928 pages
85h 29m
English
O'Reilly Media, Inc.
Content preview from Oracle in a Nutshell

Logical Conditions

A logical condition is a condition that can return one of three values—TRUE, FALSE, or UNKNOWN (which, in Oracle, is known as NULL). The three logical conditions supported by Oracle are NOT, AND, and OR.

The results of the NOT conditions for three-state logic (TRUE, FALSE, and UNKNOWN or NULL) are:

NOT TRUE = FALSE
NOT FALSE = TRUE
NOT UNKNOWN = UNKNOWN (NULL)

Table B-2 provides the results of comparisons with combinations of these conditions:

Table B-2. Combinations of logical conditions

Comparison

Value

TRUE

FALSE

UNKNOWN

AND

TRUE

TRUE

FALSE

UNKNOWN

FALSE

FALSE

FALSE

FALSE

UNKNOWN

UNKNOWN

FALSE

UNKNOWN

OR

TRUE

TRUE

TRUE

TRUE

FALSE

TRUE

FALSE

UNKNOWN

UNKNOWN

TRUE

UNKNOWN

UNKNOWN

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

Oracle Internals

Oracle Internals

Donald K. Burleson
Oracle PL/SQL

Oracle PL/SQL

Lewis Cunningham
Oracle Essentials: Oracle9i, Oracle8i and Oracle8, Second Edition

Oracle Essentials: Oracle9i, Oracle8i and Oracle8, Second Edition

Rick Greenwald, Robert Stackowiak, Jonathan Stern

Publisher Resources

ISBN: 0596003366Errata Page