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Fourth Generation Languages and OR extensions to SQL. University of California, Berkeley School of Information Management and Systems SIMS 257: Database Management. Review PHP (a bit more is working now)… Fourth Generation Languages Object-Relational Extensions to SQL. Lecture Outline.

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Fourth generation languages and or extensions to sql l.jpg

Fourth Generation Languages and OR extensions to SQL

University of California, Berkeley

School of Information Management and Systems

SIMS 257: Database Management


Lecture outline l.jpg

Review

PHP (a bit more is working now)…

Fourth Generation Languages

Object-Relational Extensions to SQL

Lecture Outline


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PHP

  • PHP is an Open Source Software project with many programmers working on the code.

    • Commonly paired with MySQL, another OSS project

    • Free

    • Both Windows and Unix support

  • Estimated that more than 250,000 web sites use PHP as an Apache Module.


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PHP Syntax

  • Similar to ASP

  • Includes most programming structures (Loops, functions, Arrays, etc.)

  • Loads HTML form variables so that they are addressable by name

  • <HTML><BODY>

  • <?php

  • $myvar = “Hello World”;

  • echo $myvar ;

  • ?>

  • </BODY></HTML>


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Combined with MySQL

  • DBMS interface appears as a set of functions:

<HTML><BODY>

<?php

$db = mysql_connect(“localhost”, “root”);

mysql_select_db(“mydb”,$db);

$result = mysql_query(“SELECT * FROM employees”, $db);

printf(“First Name: %s <br>\n”, mysql_result($result, 0 “first”);

printf(“Last Name: %s <br>\n”, mysql_result($result, 0 “last”);

?></BODY></HTML>


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Examples with Diveshop


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Fourth Generation Languages

  • 1st Generation -- Machine Language

  • 2nd Generation -- Assembly Languages

  • 3rd Generation -- High-Level Languages

  • 4th Generation -- Non-Procedural Languages

  • 5th Generation -- ?? Knowledge-based ?? Natural Language ??

  • Where do Object-Oriented Languages fit??


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Chauffeurs

  • In the early days of the US car industry, production volumes were growing fast, and a well-known sociologist was asked to predict the total number of automobiles that would ever be manufactured. After a great deal of study, the sociologist reported that no more than 2 million would be manufactured in the life cycle of the car. If the car lasted ten years on average, the maximum annual production would never exceed 200,000. This conclusion was based on the much-researched figure that no more than 2 million people would be willing to serve as chauffeurs.

From James Martin - Fourth Generation Languages


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Fourth Generation Languages

  • In the database environment these are used for creation of database applications

  • To speed up the application building process

  • To make applications easy and quick to change

  • To minimize debugging problems

  • To generate bug-free code from high-level expressions of requirement

  • To make languages user-friendly so that “end-users” can solve their own problems and put computers to work.


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Basic Principles of 4GLs

  • The Principle of Minimum Work

  • The Principle of Minimum Skill

  • The Principle of avoiding alien syntax and mnemonics

  • The Principle of Minimum Time

  • The Principle of Minimum errors

  • The Principle of Minumum Maintenance

  • The Principle of Maximum Results

From James Martin - Fourth Generation Languages


Properties of 4gls l.jpg

Properties of 4GLs

  • User Friendly

  • A nonprofessional programmer can obtain results with it

  • It employs the database management system directly

  • Programs for most applications can be created with 10 times fewer instructions than in a Third Generation Language


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More Properties of 4GLs

  • Non procedural code is used wherever possible

  • It make intelligent default assumptions about what the user wants wherever possible

  • It is designed for online operation

  • It enforces or encourages structured code

  • It makes it easy to understand and maintain another person’s code


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More Properties of 4GLs

  • Non-DP users can learn a subset of the language in a short course

  • It is designed for easy debugging

  • Prototypes can be created and modified quickly

  • Results can be obtained in an order of magnitude less time than with a 3GL for most applications


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Selection Criteria for 4GLs

  • Is it intended for routine computing of ad hoc decision making

  • Is it intended for end users or DP professionals? (many 4GLs are appropriate for both)

  • Does it require the skills of a programmer, or can an analyst who does not program in a 3GL use it.


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Selection Criteria for 4GLs

  • Which of the following features does it provide?

    • Simple queries

    • Simple queries and updates

    • Complex queries

    • Complex queries and updates

    • The ability to create a database quickly

    • Intelligent database operations, where the change of one value in the database causes other operations to occur automatically, such as validity checks, cross references, and the updating of related values.


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Selection Criteria for 4GLs

  • Which of the following features does it provide?(cont)

    • Generation of data-entry screens for key-entry operators (with validity checks)

    • Generation of data-update screens for key-entry operators (with validity checks)

    • A procedural language giving full programming capability

    • Graphics techniques for application design

    • Spreadsheet manipulation

    • Multidimensional matrix manipulation

    • Report generation

    • Graphics generation


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Selection Criteria for 4GLs

  • Which of the following features does it provide?(cont)

    • Graphics manipulation

    • Decision support for what-if questions

    • Mathematical analysis tools

    • Financial analysis tools

    • Other decision-support tools

    • Text manipulation

    • Electronic Mailbox

  • Is it on-line or off-line?

  • Does it run on mainframes, minicomputers or personal computers?

  • Can it access mainframe or remote databases

  • Is it genuinely easy to use

  • Can results be obtained with it very quickly?


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Components of a 4GL

for building routine applications…

Application

Parameters

Data

Specification

Report

Specification

Feedback

Screen

Specification

Rules

Specification

Procedural

facility

Testing

tools/debugger

Interpreter

Optimizing

compiler


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5GLs -- Natural Language

  • Possibilities

  • Problems


Natural language l.jpg

Natural Language

  • Advantages of using NL

    • It encourages untrained users to start

    • It encourages upper-management use of computers

    • It reduces the time taken learning complex syntax

    • It lessens the frustration, bewilderment and anger caused by BAD COMMAND responses

    • It is likely to extend greatly the usage of computers

James Martin, Fourth Generation Languages, 1985


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It lacks precision

It is not good for expressing precise and complex logic

It is not good for expressing neat structures

It encourages semantic overshoot

It should be combined with other dialogue contructs that aid in the representation of precise logic and structures

Natural Language

Disadvantages of using NL

Appropriate response to the

disadvantage

James Martin, Fourth Generation Languages, 1985


Natural language22 l.jpg

It takes substantial time to key in sentences

Ambiguities are possible

Substantial processing is needed

Sentences and words can be abbreviated

Speech input as well as typed input will be used

The computer should detect and resolve ambiguities

The processing should be on PC workstations. Processing is dropping rapidly in cost.

Natural Language

Disadvantages of using NL

Appropriate response to the

disadvantage

James Martin, Fourth Generation Languages, 1985


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Assumptions and Issues

  • Why 4GLs?

    • Are they still appropriate?

    • Are they still useful?

  • Is Cold Fusion a 4GL?

  • What about PHP?

  • Who needs them?


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Object Relational Databases

  • Background

  • Object Definitions

    • inheritance

  • User-defined datatypes

  • User-defined functions


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Object Relational Databases

  • Began with UniSQL/X unified object-oriented and relational system

  • Some systems (like OpenODB from HP) were Object systems built on top of Relational databases.

  • Miro/Montage/Illustra built on Postgres.

  • Informix Buys Illustra. (DataBlades)

  • Oracle Hires away Informix Programmers. (Cartridges)


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Object Relational Data Model

  • Class, instance, attribute, method, and integrity constraints

  • OID per instance

  • Encapsulation

  • Multiple inheritance hierarchy of classes

  • Class references via OID object references

  • Set-Valued attributes

  • Abstract Data Types


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Object Relational Extended SQL (Illustra)

  • CREATE TABLE tablename {OF TYPE Typename}|{OF NEW TYPE typename} (attr1 type1, attr2 type2,…,attrn typen) {UNDER parent_table_name};

  • CREATE TYPE typename (attribute_name type_desc, attribute2 type2, …, attrn typen);

  • CREATE FUNCTION functionname (type_name, type_name) RETURNS type_name AS sql_statement


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Object-Relational SQL in ORACLE

  • CREATE (OR REPLACE) TYPE typename AS OBJECT (attr_name, attr_type, …);

  • CREATE TABLE OF typename;


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Example

  • CREATE TYPE ANIMAL_TY AS OBJECT (Breed VARCHAR2(25), Name VARCHAR2(25), Birthdate DATE);

  • Creates a new type

  • CREATE TABLE Animal of Animal_ty;

  • Creates “Object Table”


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Constructor Functions

  • INSERT INTO Animal values (ANIMAL_TY(‘Mule’, ‘Frances’, TO_DATE(‘01-APR-1997’, ‘DD-MM-YYYY’)));

  • Insert a new ANIMAL_TY object into the table


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Selecting from an Object Table

  • Just use the columns in the object…

  • SELECT Name from Animal;


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More Complex Objects

  • CREATE TYPE Address_TY as object (Street VARCHAR2(50), City VARCHAR2(25), State CHAR(2), zip NUMBER);

  • CREATE TYPE Person_TY as object (Name VARCHAR2(25), Address ADDRESS_TY);

  • CREATE TABLE CUSTOMER (Customer_ID NUMBER, Person PERSON_TY);


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What Does the Table Look like?

  • DESCRIBE CUSTOMER;

  • NAME TYPE

  • -----------------------------------------------------

  • CUSTOMER_ID NUMBER

  • PERSON NAMED TYPE


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Inserting

  • INSERT INTO CUSTOMER VALUES (1, PERSON_TY(‘John Smith’, ADDRESS_TY(‘57 Mt Pleasant St.’, ‘Finn’, ‘NH’, 111111)));


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Selecting from Abstract Datatypes

  • SELECT Customer_ID from CUSTOMER;

  • SELECT * from CUSTOMER;

CUSTOMER_ID PERSON(NAME, ADDRESS(STREET, CITY, STATE ZIP))

---------------------------------------------------------------------------------------------------

1 PERSON_TY(‘JOHN SMITH’, ADDRESS_TY(‘57...


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Selecting from Abstract Datatypes

  • SELECT Customer_id, person.name from Customer;

  • SELECT Customer_id, person.address.street from Customer;


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Updating

  • UPDATE Customer SET person.address.city = ‘HART’ where person.address.city = ‘Briant’;


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Functions

  • CREATE [OR REPLACE] FUNCTION funcname (argname [IN | OUT | IN OUT] datatype …) RETURN datatype (IS | AS) {block | external body}


Example39 l.jpg

Example

Create Function BALANCE_CHECK (Person_name IN Varchar2) RETURN NUMBER is BALANCE NUMBER(10,2) BEGIN

SELECT sum(decode(Action, ‘BOUGHT’, Amount, 0)) - sum(decode(Action, ‘SOLD’, amount, 0)) INTO BALANCE FROM LEDGER where Person = PERSON_NAME;

RETURN BALANCE;

END;


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Example

  • Select NAME, BALANCE_CHECK(NAME) from Worker;


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TRIGGERS

  • Create TRIGGER UPDATE_LODGING INSTEAD OF UPDATE on WORKER_LODGING for each row BEGIN

  • if :old.name <> :new.name then update worker set name = :new.name where name = :old.name;

  • end if;

  • if :old.lodging <> … etc...


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Next Week

  • Database Administration

  • More on Database Applications


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