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Fourth Generation Languages and PHP. University of California, Berkeley School of Information Management and Systems SIMS 257: Database Management. Review: Security and Integrity Fourth Generation Languages More on PHP and Web Interfaces. Lecture Outline. Review: Security and Integrity

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Fourth generation languages and php

Fourth Generation Languages and PHP

University of California, Berkeley

School of Information Management and Systems

SIMS 257: Database Management


Lecture outline

Review: Security and Integrity

Fourth Generation Languages

More on PHP and Web Interfaces

Lecture Outline


Lecture outline1

Review: Security and Integrity

Fourth Generation Languages

More on PHP and Web Interfaces

Lecture Outline


Security and integrity functions in database administration

Security and Integrity Functions in Database Administration

  • Data Integrity

  • Security Management

  • Backup and Recovery


Security and integrity functions in database administration1

Security and Integrity Functions in Database Administration

  • Data Integrity

  • Security Management

  • Backup and Recovery


Integrity constraints review

Integrity Constraints (review)

  • The constraints we wish to impose in order to protect the database from becoming inconsistent.

  • Five types

    • Required data

    • attribute domain constraints

    • entity integrity

    • referential integrity

    • enterprise constraints


Data and domain integrity

Data and Domain Integrity

  • This is now increasing handled by the database. In Oracle, for example, when defining a table you can specify:

  • CREATE TABLE table-name (

    attr2 attr-type NOT NULL, forbids NULL values

    attrN attr-type CHECK (attrN = UPPER(attrN) verifies that the data meets certain criteria

    attrO attr-type DEFAULT default_value); Supplies default values


Referential integrity

Referential Integrity

  • Ensures that dependent relationships in the data are maintained. In Oracle, for example:

  • CREATE TABLE table-name (

    attr1 attr-type PRIMARY KEY,

    attr2 attr-type NOT NULL,

    …, attrM attr-type REFERENCES owner.tablename(attrname) ON DELETE CASCADE, …


Concurrency control

Concurrency Control

  • The goal is to support access by multiple users to the same data, at the same time

  • It must assure that the transactions are serializable and that they are isolated

  • It is intended to handle several problems in an uncontrolled system

  • Specifically:

    • Lost updates

    • Inconsistent data states during access

    • Uncompleted (or committed) changes to data


Transaction control in oracle

Transaction Control in ORACLE

  • Transactions are sequences of SQL statements that ORACLE treats as a unit

    • From the user’s point of view a private copy of the database is created for the duration of the transaction

  • Transactions are started with SET TRANSACTION, followed by the SQL statements

  • Any changes made by the SQL are made permanent by COMMIT

  • Part or all of a transaction can be undone using ROLLBACK


Transactions in oracle

Transactions in ORACLE

  • COMMIT;

  • SET TRANSACTION READ ONLY;

  • SELECT NAME, ADDRESS FROM WORKERS;

  • SELECT MANAGER, ADDRESS FROM PLACES;

  • COMMIT;

  • Freezes the data for the user in both tables before either select retrieves any rows, so that changes that occur concurrently will not show up

  • Commits before and after ensure any uncompleted transactions are finish, and then release the frozen data when done


Transactions in oracle1

Transactions in ORACLE

  • Savepoints are places in a transaction that you may ROLLBACK to (called checkpoints in other DBMS)

    • SET TRANACTION…;

    • SAVEPOINT ALPHA;

    • SQL STATEMENTS…

    • IF (CONDITION) THEN ROLLBACK TO SAVEPOINT ALPHA;

    • SAVEPOINT BETA;

    • SQL STATEMENTS…

    • IF …;

    • COMMIT;


Database security

Database Security

  • Views or restricted subschemas

  • Authorization rules to identify users and the actions they can perform

  • User-defined procedures (and rule systems) to define additional constraints or limitations in using the database

  • Encryption to encode sensitive data

  • Authentication schemes to positively identify a person attempting to gain access to the database


Views

Views

  • A subset of the database presented to some set of users

    • SQL:

      CREATE VIEW viewname AS SELECT field1, field2, field3,…, FROM table1, table2 WHERE <where clause>;

    • Note: “queries” in Access function as views


Restricted views

Restricted Views

  • Main relation has the form:

U = unclassified : S = Secret : TS = Top Secret


Restricted views1

Restricted Views

S-view of the data

U-view of the data


Disaster recovery planning

Disaster Recovery Planning

Risk

Analysis

Recovery

Strategies

Plan

Maintenance

Testing and

Training

Budget &

Implement

Procedures

Development

From Toigo “Disaster Recovery Planning”


Threats to assets and functions

Threats to Assets and Functions

  • Water

  • Fire

  • Power Failure

  • Mechanical breakdown or software failure

  • Accidental or deliberate destruction of hardware or software

    • By hackers, disgruntled employees, industrial saboteurs, terrorists, or others


Threats

Threats

  • Between 1967 and 1978 fire and water damage accounted for 62% of all data processing disasters in the U.S.

  • The water damage was sometimes caused by fighting fires

  • More recently improvements in fire suppression (e.g., Halon) for DP centers has meant that water is the primary danger to DP centers


Lecture outline2

Review: Security and Integrity

Fourth Generation Languages

More on PHP and Web Interfaces

Lecture Outline


Fourth generation languages

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??


Chauffeurs

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


Fourth generation languages1

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.


Basic principles of 4gls

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

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


More properties of 4gls

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


More properties of 4gls1

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


Selection criteria for 4gls

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.


Selection criteria for 4gls1

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.


Selection criteria for 4gls2

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


Selection criteria for 4gls3

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?


Components of a 4gl

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


5gls natural language

5GLs -- Natural Language

  • Possibilities

  • Problems


Natural language

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


Natural language1

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 language2

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


Assumptions and issues

Assumptions and Issues

  • Why 4GLs?

    • Are they still appropriate?

    • Are they still useful?

  • Is Cold Fusion a 4GL?

  • What about PHP?

  • Who needs them?


Lecture outline3

Review: Security and Integrity

Fourth Generation Languages

More on PHP and Web Interfaces

Lecture Outline


Fourth generation languages and php

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.


Php syntax

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>


Combined with mysql

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>


Diveshop php

Diveshop PHP

  • The same interface (with minor differences) that we saw for ColdFusion has been implemented in PHP and MySQL

  • Address for the example is

    • http://dream.sims.berkeley.edu/~ray/Diveshop/index.php3

  • To setup your own MySQL database you will need to use the “my.sims” interface to request a MySQL account and PHP access


Diveshop php1

Diveshop PHP

  • Setup puts a “public_html.php” directory in your home directory and you put your PHP files there

  • The PHP processor is on the “dream.sims” machine, so use that for access

  • Because the results of the PHP processing don’t include the original PHP instructions we will look at the different PHP scripts that generated the pages


Simple search

Simple search

<?

mysql_connect("localhost","ray","ray");

$query = "SELECT * FROM DIVECUST";

$result = mysql_db_query("ray", $query);

if ($result) {

echo "Got results...";

while ($r = mysql_fetch_array($result)) {

echo "<tr>";

$tmp = $r["Customer_No"];

echo "<td>$tmp</td>";

$tmp = $r["Name"];

echo "<td>$tmp</td>";

$tmp = $r["Street"];

echo "<td>$tmp</td>";

$tmp = $r["City"];

echo "<td>$tmp</td>";

$tmp = $r["State_Prov"];

echo "<td>$tmp</td>";

$tmp = $r["Zip_Postal_Code"];

echo "<td>$tmp</td>";

$tmp = $r["Country"];

echo "<td>$tmp</td>";

$tmp = $r["Phone"];

echo "<td>$tmp</td>";

$tmp = $r["First_Contact"];

echo "<td>$tmp</td>";

echo "</tr>";

}

} else {

echo "<p>No Results???";

}

?>

</table></body></html>

<html>

<head>

<title>Example PHP Database: DiveShop</title>

</head>

<body>

<CENTER>

<font size=+2 face="arial,helvetica">PHP DiveShop Customers</font>

<p>

<IMG SRC="LOGO.GIF" >

</CENTER>

<p>

<table border=0 cellpadding=2 cellspacing=2 width=110%>

<tr>

<td>ID #</td>

<td><b> <font face="arial,helvetica">Name</td>

<td>Street</td>

<td>City</td>

<td>State/Prov</td>

<td>Zip</td>

<td>Country</td>

<td>Phone</td>

<td>First Contact</td>

</tr>

<tr><td colspan=9>

<hr width=100% noshade>

</td></tr>


Details

Details

<?

mysql_connect("localhost","ray","ray");

$query = "SELECT * FROM DIVECUST";

$result = mysql_db_query("ray", $query);

if ($result) {

echo "Got results...";

while ($r = mysql_fetch_array($result)) {

echo "<tr>";

$tmp = $r["Customer_No"];

echo "<td>$tmp</td>";

$tmp = $r["Name"];

…etc…

}

} else {

echo "<p>No Results???";

}

?>


Adding data

Adding data

<!doctype html public "-//w3c//dtd html 4.0 transitional//en">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">

<meta name="GENERATOR" content="Mozilla/4.75 [en]C-CCK-MCD (WinNT; U) [Netscape]">

<title>New Customer Information

</title>

</head>

<body bgcolor="#FFFFFF">

<h2>

<img SRC="LOGO.GIF" align=LEFT><b><font color="#0000FF"><font size=+4>DiveShop</font></font></b>:

New Customer Input</h2>

<hr><form ACTION="procform.php3" METHOD=GET>

<h2>

Please input your information below</h2>

Name:&nbsp;&nbsp;&nbsp;&nbsp;<input NAME=name TYPE=TEXT SIZE=100>

<br>Street:&nbsp;&nbsp;&nbsp;&nbsp;<input NAME=street TYPE=TEXT SIZE=100>

<br>City:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<input NAME=city TYPE=TEXT SIZE=100>

<br>State:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<input NAME=state TYPE=TEXT SIZE=2>

<br>ZIP:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<input NAME=Zip TYPE=TEXT SIZE=12>

<br>Country:&nbsp;<input NAME=Country TYPE=TEXT SIZE=50>

<br>Phone:&nbsp;&nbsp;&nbsp;&nbsp;<input NAME=Phone TYPE=TEXT SIZE=50>

<p><input TYPE=submit VALUE=" Submit Data "><input type=reset VALUE=" Clear Fields "></form>

<hr>

</body>

</html>


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