Object-PL/SQL: Difference between revisions

Revision as of 15:05, 16 March 2016

Revision as of 04:56, 17 March 2016

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=== Example 1 ===

A simple example of object-oriented PL/SQL<ref>{{cite web|url=http://www.adp-gmbh.ch/ora/plsql/oo/example_1.html|title=Object Oriented Oracle, example 1|publisher=René Nyffenegger's collection of things on the web|accessdate=19 April 2012}}</ref>
<source lang="plsqlplpgsql">

create or replace type base_type as object (

a number,

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) instantiable not final;

/</source>

Now, the type's implementation is created. The implementation defines how the type's functions, procedures and how explicit constructors behave:<source lang="plsqlplpgsql">

create or replace type body base_type as

constructor function base_type return self as result is

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end;

/</source>

We're ready to derive from base_type. The keyword for deriving is under. The derived type defines a new attribute (named: m) and overrides func.<source lang="plsqlplpgsql">

create or replace type deriv_type under base_type (

m number,

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);

/</source>

As is the case with base types, the overridden methods in the derived type must be implemented:
<source lang="plsqlplpgsql">

create or replace type body deriv_type as

overriding member function func return number is

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end;

/</source>

The created types can be instantiated and methods can be called:
<source lang="plsqlplpgsql">

declare

b1 base_type :=base_type();

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/</source>

Results

* 0

* 4

* 24

* 30

The created types have become real types and can be used in tables:
<source lang="plsqlplpgsql">

create table table_base (

b base_type

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</source>

Results:

* 0

* 72

<source lang="plsqlplpgsql">

select avg(t.b.func()) from table_base t;

</source>

Result:

* 36

=== Example 2 ===