SLIDE 1IS Fall 2002 Fourth Generation Languages and OR extensions to SQL University of California, Berkeley School of Information Management and Systems SIMS 257: Database Management

SLIDE 2IS Fall 2002 Lecture Outline Review –PHP (a bit more is working now)… Fourth Generation Languages Object-Relational Extensions to SQL

SLIDE 3IS Fall 2002 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.

SLIDE 4IS Fall 2002 PHP Syntax Similar to ASP Includes most programming structures (Loops, functions, Arrays, etc.) Loads HTML form variables so that they are addressable by name <?php $myvar = “Hello World”; echo $myvar ; ?>

SLIDE 5IS Fall 2002 Combined with MySQL DBMS interface appears as a set of functions: <?php $db = mysql_connect(“localhost”, “root”); mysql_select_db(“mydb”,$db); $result = mysql_query(“SELECT * FROM employees”, $db); printf(“First Name: %s \n”, mysql_result($result, 0 “first”); printf(“Last Name: %s \n”, mysql_result($result, 0 “last”); ?>

SLIDE 6IS Fall 2002 Examples with Diveshop

SLIDE 7IS Fall 2002 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??

SLIDE 8IS Fall 2002 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

SLIDE 9IS Fall 2002 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.

SLIDE 10IS Fall 2002 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

SLIDE 11IS Fall 2002 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

SLIDE 12IS Fall 2002 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

SLIDE 13IS Fall 2002 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

SLIDE 14IS Fall 2002 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.

SLIDE 15IS Fall 2002 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.

SLIDE 16IS Fall 2002 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

SLIDE 17IS Fall 2002 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?

SLIDE 18IS Fall 2002 Components of a 4GL Application Parameters Testing tools/debugger Interpreter Optimizing compiler Rules Specification Data Specification Report Specification Screen Specification Procedural facility Feedback for building routine applications…

SLIDE 19IS Fall GLs -- Natural Language Possibilities Problems

SLIDE 20IS Fall 2002 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

SLIDE 21IS Fall 2002 Natural Language 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 James Martin, Fourth Generation Languages, 1985 Disadvantages of using NL Appropriate response to the disadvantage

SLIDE 22IS Fall 2002 Natural Language 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. James Martin, Fourth Generation Languages, 1985 Disadvantages of using NL Appropriate response to the disadvantage

SLIDE 23IS Fall 2002 Assumptions and Issues Why 4GLs? –Are they still appropriate? –Are they still useful? Is Cold Fusion a 4GL? What about PHP? Who needs them?

SLIDE 24IS Fall 2002 Object Relational Databases Background Object Definitions –inheritance User-defined datatypes User-defined functions

SLIDE 25IS Fall 2002 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)

SLIDE 26IS Fall 2002 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

SLIDE 27IS Fall 2002 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

SLIDE 28IS Fall 2002 Object-Relational SQL in ORACLE CREATE (OR REPLACE) TYPE typename AS OBJECT (attr_name, attr_type, …); CREATE TABLE OF typename;

SLIDE 29IS Fall 2002 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”

SLIDE 30IS Fall 2002 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

SLIDE 31IS Fall 2002 Selecting from an Object Table Just use the columns in the object… SELECT Name from Animal;

SLIDE 32IS Fall 2002 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);

SLIDE 33IS Fall 2002 What Does the Table Look like? DESCRIBE CUSTOMER; NAME TYPE CUSTOMER_ID NUMBER PERSON NAMED TYPE

SLIDE 34IS Fall 2002 Inserting INSERT INTO CUSTOMER VALUES (1, PERSON_TY(‘John Smith’, ADDRESS_TY(‘57 Mt Pleasant St.’, ‘Finn’, ‘NH’, )));

SLIDE 35IS Fall 2002 Selecting from Abstract Datatypes SELECT Customer_ID from CUSTOMER; SELECT * from CUSTOMER; CUSTOMER_ID PERSON(NAME, ADDRESS(STREET, CITY, STATE ZIP)) PERSON_TY(‘JOHN SMITH’, ADDRESS_TY(‘57...

SLIDE 36IS Fall 2002 Selecting from Abstract Datatypes SELECT Customer_id, person.name from Customer; SELECT Customer_id, person.address.street from Customer;

SLIDE 37IS Fall 2002 Updating UPDATE Customer SET person.address.city = ‘HART’ where person.address.city = ‘Briant’;

SLIDE 38IS Fall 2002 Functions CREATE [OR REPLACE] FUNCTION funcname (argname [IN | OUT | IN OUT] datatype …) RETURN datatype (IS | AS) {block | external body}

SLIDE 39IS Fall 2002 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;

SLIDE 40IS Fall 2002 Example Select NAME, BALANCE_CHECK(NAME) from Worker;

SLIDE 41IS Fall 2002 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...

SLIDE 42IS Fall 2002 Next Week Database Administration More on Database Applications