View source for Object-PL/SQL

'''Object-PL/SQL''' ('''[[Object-oriented programming|Object]]-Procedural Language/[[Structured Query Language]]''' or simply '''O-PL/SQL''') is a methodology of using the [[Oracle Corporation]]'s [[Procedural programming|procedural]] extension [[programming language|language]] for [[SQL]] and the [[Oracle Database|Oracle relational database]].<ref name="CITDK">{{cite web|url=http://www.cit.dk/cot/reports/reports/Case4/18/cot-4-18.pdf|title=Experiences with Object Oriented Development in PL/SQL|author=Lassan, Alan R.|last2=Due, Jacob Steen|date=13 June 2000|publisher=The danish National Center for IT Research|url-status=dead|archive-url=https://web.archive.org/web/20101224020624/http://www.cit.dk/cot/reports/reports/Case4/18/cot-4-18.pdf|archive-date=24 December 2010|access-date=15 April 2012}}</ref> <ref>{{Cite journal|last1=Centre For|last2=Allan R. Lassen|last3=Jacob Steen Due|date=2000|title=Experiences with Object Oriented Development in PL/SQL|citeseerx=10.1.1.38.5122}}</ref>  The additional features from version 7 and other improvements, lead to one of the large-scale environment implementations of the [[object-oriented database]] paradigm.<ref name="DBAORA">{{cite web|url=http://www.dba-oracle.com/t_edb_pl_sql_features_release.htm|title=PL/SQL Features by Release|author=Cunningham, Lewis|publisher=Burleson Consulting|access-date=15 April 2012}}</ref>

Although PL/SQL's general [[Syntax (programming languages)|syntax]] formerly used to resemble that of [[Ada (programming language)|Ada]] or [[Pascal (programming language)|Pascal]], there were many improvements that mainly include the ''Java embedding code''<ref name="STKOVER">{{cite web|url=https://stackoverflow.com/questions/70072/when-should-you-use-java-stored-procedures-with-an-oracle-database-what-are|title=When Should you use Java Stored Procedures with an Oracle Database, what are the Drawbacks?|publisher=Stack Overflow|access-date=15 April 2012}}</ref> and the ''object-oriented syntax''<ref name="ETUT">{{cite web|url=http://etutorials.org/SQL/Oracle+PL+SQL+Language+Pocket+Reference/Chapter+1.+Oracle+PLSQL+Language+Pocket+Reference/1.16+Oracles+Object-Oriented+Features/|title=Oracle's Object-Oriented Features|publisher=etutorial.org|access-date=16 April 2012}}</ref> inside the SQL.

The mixing and embedding of [[Database trigger|triggers]] and [[stored procedure]]s was one of the breakthrough points up to support the use of [[PL/SQL]] in a ''OO'' paradigm.<ref name="SAMS">Benett, 2002:144</ref> The inclusion in the SQL syntax of statements such as {{mono|[class].[object]}}, and the implementation of the object ''type''<ref name="TOP10"/> (like any OO language), completed the minimum requisites to a mapping approach in an extended SQL language without use of [[Persistence framework|specific mapping software]].<ref name="BALES">Bales, 2007:107-209</ref>

== Autonomy, notoriety and importance of O-PL/SQL ==
The O-PSL/SQL isn't simply the use a version of a programming language but it's identified as ''how to use it'', and it defines the autonomy of the theme.<ref name="JAVA2">{{cite web|url=http://www.java2s.com/Tutorial/Oracle/0620__Object-Oriented/UseObjectPLSQL.htm|title=Use Object PL/SQL|publisher=java2s.com|access-date=19 April 2012}}</ref> Each version of PL/SQL, starting from 7, brings so many innovations that it's impossible to treat such usages as sub-themes of PL/SQL. So big is that revolution that it establishes a real borderline between the language, that can be used as formerly, and the OO approach inside itself. It's just this approach that makes the theme important and the large-scale using has brought its notoriety.<ref name="STEVE">Feuerstein, 2009</ref>

== A confusing of ''objects'' ==
There can be confusion of the notions of ''object of DBMS'' and of ''class object''. This is very important as we live with both significances in one language. It's necessary to identify when the documentation refers to an ''object'' as one of the two definitions.

''Database objects'' are concepts that refer to [[Relational model|relational]] or sequential databases and persist being valid in new models. ''Tables'', ''triggers'', ''columns'', ''indexes'' are examples of database objects,<ref name="TOP10">{{cite web|url=http://www.codeproject.com/Articles/43629/Top-10-steps-to-optimize-data-access-in-SQL-Server|title=Optimize Database Files and Apply Partitioning|author=Shubho, Al-Farooque|date=8 November 2009|publisher=The Code Project|access-date=19 April 2012}}</ref> which are present in O-PL/SQL, but with the same meaning of the notion of [[Java (programming language)|Java]] objects, specifically an element of a set that has its existence beginning from an instantiation of a class.

== The PL/SQL ==
{{Main article|PL/SQL}}
PL/SQL is the extended SQL language used by [[Oracle Database]].

PL/SQL is available in Oracle Database (since version 7), [[TimesTen|TimesTen in-memory database]] (since version 11.2.1), and [[IBM Db2]] (since version 9.7).<ref name="IBM">{{cite web|url=http://www.ibm.com/developerworks/data/library/techarticle/dm-0907oracleappsondb2/index.html|title=DB2 10: Run Oracle applications on DB2 10 for Linux, UNIX, and Windows|publisher=IBM|access-date=20 April 2012}}</ref>

O-PL/SQL allows the definition of classes and instantiating these as objects, 
thus creating user-defined datatypes as writing constructors, beyond using Java in stored procedures and triggers.

== Examples of uses of syntax of O-PL/SQL ==
Here is a small set of examples of O-PL/SQL syntax, extracted from the official documentation<ref name="ORADOC">{{cite web|url=http://docs.oracle.com/|title=Oracle Documentatio|publisher=Oracle|access-date=19 April 2012}}</ref> and other sources:

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|access-date=19 April 2012}}</ref>
<syntaxhighlight lang="plpgsql">
create or replace type base_type as object (
  a number,
  constructor function base_type return self as result,
  member function  func return number,
  member procedure proc (n number)
) instantiable not final;
/</syntaxhighlight>
Now, the type's implementation is created. The implementation defines how the type's functions, procedures and how explicit constructors behave:<syntaxhighlight lang="plpgsql">
create or replace type body base_type as 
  constructor function base_type return self as result is
  begin
    a:=0;
    return;
  end base_type;

  member function func return number is
  begin
    return a;
  end func;

  member procedure proc (n number) as
  begin
    a:=n;
  end proc;
end;
/</syntaxhighlight>
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.<syntaxhighlight lang="plpgsql">
create or replace type deriv_type under base_type (
  m number,
  overriding member function func return number
);
/</syntaxhighlight>
As is the case with base types, the overridden methods in the derived type must be implemented:
<syntaxhighlight lang="plpgsql">
create or replace type body deriv_type as
  overriding member function func return number is
  begin
    return m*a;
  end;
end;
/</syntaxhighlight>
The created types can be instantiated and methods can be called:
<syntaxhighlight lang="plpgsql">
declare
  b1 base_type :=base_type();
  b2 base_type :=base_type(4);
  d1 deriv_type:=deriv_type(5,6);
  d2 deriv_type:=deriv_type(5,6);
begin
  dbms_output.put_line(b1.func);
  dbms_output.put_line(b2.func);

  d1.proc(4);
  dbms_output.put_line(d1.func);
  dbms_output.put_line(d2.func);
end;
/</syntaxhighlight>
Results
 0
 4
 24
 30
The created types have become real types and can be used in tables:
<syntaxhighlight lang="plpgsql">
create table table_base (
  b base_type
);
declare
  base  base_type := base_type();
  deriv deriv_type:= deriv_type(8,9);
begin
  insert into table_base values(base);
  insert into table_base values(deriv);
end;
/
select t.b.func() from table_base t;
</syntaxhighlight>
Results:
 0
 72
<syntaxhighlight lang="plpgsql">
select avg(t.b.func()) from table_base t;
</syntaxhighlight>
Result:
 36
==See also==
* [[Relational database management system]]
* [[Component-oriented database]]
* [[Transact-SQL]]
* [[Database management system]]
== Bibliography ==
* {{cite book|url=https://books.google.com/books?id=1RwFA-vlwX8C&q=mixing+java+in+pl%2Fsql+procedures+and+triggers&pg=PA144|last=Bennett|first=Mathew|title=Programming Oracle Developer|edition=1|place=Indianapolis|publisher=Sams|year=2002|pages=348|isbn=0672321106}}
* {{cite book|url=https://books.google.com/books?id=FqUKI3MSuHYC|last=Bales|first=Donals|title=PL/SQL from Novice to Professional|edition=1|place=New York|publisher=Apress|year=2007|isbn=978-1590598825|pages=469}}
* {{cite book|chapter-url=http://my.safaribooksonline.com/book/databases/oracle-pl-sql/9780596805401|title=Oracle PL/SQL Programming|last1=Feuerstein|first1=Steven|last2=Pribyl|first2=Bill|place=Sebastopol|publisher=O'Reilly Media, Inc.|year=2009|isbn=9780596514464|chapter=26}}
*{{cite book|url=http://218.92.71.5:1085/trebook/book/book36/2009986047703.pdf|last1=Rahayu|first1=Wenny|last2=taniar|first2=David|last3=Pardede|first3=Eric|title=Object-Oriented Oracle|place=Hershey|publisher=IRM Press|year=2006|pages=345|isbn=1591406080|access-date=2012-04-20|archive-url=https://web.archive.org/web/20160303223746/http://218.92.71.5:1085/trebook/book/book36/2009986047703.pdf|archive-date=2016-03-03|url-status=dead}}

==References==
{{reflist}}

== External sources ==
* [https://web.archive.org/web/20120917012254/http://elearning.algonquincollege.com/coursemat/dat2355d/oracle-oo.html Examples of O-Pl/SQL]
* Another example of stored procedure in Java embedded in Oracle Documentation: {{anchor|ORA2}}{{cite web|url=http://docs.oracle.com/cd/B19306_01/java.102/b14187/chthree.htm#CACFGDCI|title=Calling Java Methods in Oracle Database|publisher=Oracle|access-date=20 April 2012}}

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