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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

Programmer-Defined Subtypes

PL/SQL allows you to define unconstrained scalar subtypes. An unconstrained subtype provides an alias to the original underlying datatype; for example:

CREATE OR REPLACE PACKAGE std_types
IS
   -- Declare standard types as globals.
   SUBTYPE dollar_amt_t IS NUMBER;
END std_types;

CREATE OR REPLACE PROCEDURE process_money
IS
   -- Use the global type declared above.
   credit std_types.dollar_amt_t;
   ...

A constrained subtype limits or constrains the new datatype to a subset of the original datatype.

You can define your own constrained subtypes in your programs (starting with Oracle8i), as you would typically do in the package section:

PACKAGE std_types
IS
   SUBTYPE currency_t IS NUMBER (15, 2);

END;
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Publisher Resources

ISBN: 0596003366Errata Page