December 2002
Intermediate to advanced
928 pages
85h 29m
English
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;