Computer Programming and Database Handout

MIS 315 - Bsharah

Computer Programming and Database Handout


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Contents

• Section A: Programming Basics• Section B: Procedural Programming• Section C: Object-Oriented Programming• Section D: Declarative Programming• Section E: Secure Programming• Section F: Database Programming


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Section A: Programming Basics

• Computer Programming and Software Engineering• Programming Languages and Paradigms• Program Planning• Program Coding • Programming Tools• Program Testing and Documentation


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Computer Programming and Software Engineering• The instructions that make up a computer program are

often referred to as code.• Programs can have millions of lines of code.

– Developed by computer programmers• Computer programming


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Computer Programming and Software Engineering


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Programming Languages and Paradigms

• Programming languages are made up of keywords and grammar rules designed for creating computer instructions.– Keywords can be combined with parameters.– Low-level languages typically include commands specific

to a particular CPU or microprocessor family.– High-level languages use command words and grammar

based on human languages.

• The programming paradigm refers to a way of conceptualizing and structuring the tasks a computer performs.


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Programming Languages

• First generation language– The lowest level programming language; composed of binary digits;

typically the only programming language understood by a CPU. – Machine language.

• Second generation language– More user friendly than first generation language; uses mnemonics for

people to use, such as ADD, SUB, MOV.– Assembly language.

• Third generation language – Requires the programmer to specify, step-by-step, exactly how the computer

must accomplish a task. Examples: C, Basic, FORTRAN.

• Fourth generation language– allows the user to specify the desired result without having to specify step-

by-step procedures. Examples: SAS, SPSS, APL.

• Fifth-generation language– Based on a declarative programming paradigm.

Lower Higher

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Programming Paradigms

• The programming paradigm refers to a way of conceptualizing and structuring the tasks a computer performs.

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Hypertext Markup Language and Extensible Markup Language• Hypertext

– An approach to data management in which data are stored in a network of nodes connected by links and are accessed through interactive browsing.

• Hyperlinks– The links that connect data nodes in hypertext.

• Hypertext document– The combination of nodes, links, and supporting indexes for any

particular topic in hypertext.

• Hypertext markup language (HTML)– The standard programming language used on the Web to create and

recognize hypertext documents.

• Extensible markup language (XML)– A programming language designed to improve the functionality of web

documents by providing more flexible and adaptable data identification.

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Comparison of HTML and XML

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Program Planning

• The problem statement defines certain elements that must be manipulated to achieve a result or goal.

• You accept assumptions as true to proceed with program planning.

• Known information helps the computer to solve a problem.

• Variables vs. constants


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Program Planning

• Problem statement - Identify the pizza with the lowest price per square inch.

• Assuming that there are two pizzas to compare, that both pizzas contain the same toppings, and that the pizzas could be round or square, and given the prices, shapes, and sizes of the two pizzas, the computer will print a message indicating which pizza has the lower price per square inch.

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Program Coding

A text editor such as Notepad allows programmers to enter lines of code using a familiar word processing interface.

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Programming Tools

• A Software Development Kit (SDK) is a collection of language-specific programming tools that enables a programmer to develop applications for a specific computer platform.

• An Integrated Development Environment (IDE) is a type of SDK that packages a set of development tools into a sleek programming application.

• A Component is a prewritten module, typically designed to accomplish a specific task.

• An API is a set of application program or operating system functions that programmers can access from within the programs they create.

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Program Testing and Documentation

• A computer program must be tested to ensure that it works correctly.

• Program errors include– Syntax errors– Runtime errors– Logic errors

• A Debugger can help a programmer read through lines of code and solve problems.


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Program Testing and Documentation

• Remarks or “comments” are a form of documentation that programmers insert into the program code.

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Section B: Procedural Programming

• Algorithms• Expressing an Algorithm• Sequence, Selection, and Repetition Controls• Procedural Languages and Applications


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Algorithms

• Set of steps for carrying out a task that can be written down and implemented.

• Start by recording the steps you take to solve the problem manually.

• Specify how to manipulate information.• Specify what the algorithm should display as a

solution.


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Algorithms

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Expressing an Algorithm

• Structured English• Pseudocode

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Expressing an Algorithm by a Flowchart

• Flowchart– The pizza program

flowchart illustrates how the computer should proceed through the instructions in the final program.

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Expressing an Algorithm - Walkthrough

• Perform a walkthrough to make sure thealgorithm works.


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Sequence, Selection, and Repetition Controls• Subroutines,

Procedures, and Functions – sections of

code that are part of the program, but not included in the main sequential execution path.

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Sequence, Selection, and Repetition Controls• Sequence Control structure


Executing a GOTO command directs the computer to a different part of the program.

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Sequence, Selection, and Repetition Controls• Selection Control structure


The computer executes a decision indicated on the flowchart by the question in the diamond shape.

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Sequence, Selection, and Repetition Controls• Repetition Control structure


To execute a loop, the computer repeats one or more commands until some condition indicates that the looping should stop.

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Procedural Languages and Applications

• Popular procedural languages include FORTRAN, COBOL, FORTH, APL, ALGOL, PL/1, Pascal, C, Ada, and BASIC.

• The procedural approach is best used for problems that can be solved by following a step-by-step algorithm.– Does not fit well with certain types of problems.

• Produces programs that run quickly and efficiently.


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Section C: Object-Oriented Programming

• Programming language that encapsulates a small amount of data with instructions about what to do with data.– Methods: the instructions about what to do with

encapsulated data objects.– Object: the combination of a small amount of data with the

data. – Encapsulation: the process of creating an object.– Reusability feature: allows classes created for one purpose

to be used in a different object-oriented program if desired.

• Object-oriented Program Structure• Object-oriented Languages and Applications


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Objects and Classes

• An Object represents an abstract or real-world entity.• A Class is a template for a group of objects with

similar characteristics.– A Class Attribute defines the characteristics of a set of

objects.• Public vs. private

attributes


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Inheritance

• Passing certain characteristics from one class to other classes.– Superclass– Subclass– Class hierarchy


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Methods and Messages

• A Method is a segment of code that defines an action.– Collect input, perform calculations, etc.– A method is activated by a message.– Can be defined along with the class they affect.

• Polymorphism refers to the ability to redefine a Method in a subclass.– Helps simplify program code.


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Object-Oriented Program Structure

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• When the pizza program runs, on-screen prompts ask for the shape, size, and price of each pizza; then the program displays a message that indicates which pizza is the best deal.


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Object-Oriented Languages and Applications• SIMULA was believed to be the first object-oriented

computer language.• The Dynabook project was the second major

development in object-oriented languages.• Popular object-oriented languages today are Ada95,

C++, (Visual Basic, and C#).• The OO paradigm results in decreased runtime

efficiency, but allows encapsulation, which hides the internal details of objects and their methods.


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Section D: Declarative Programming

• The Declarative Paradigm• Prolog Facts• Prolog Rules• Input Capabilities• Declarative Languages and Applications


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The Declarative Paradigm

• Attempts to describe a problem without specifying exactly how to arrive at a solution.– A Fact is a statement for solving a problem.– Rules describe the relationship between Facts.

• An approach to the programming process in which the programmer writes a program by specifying a set of statements and rules that define the conditions for solving the problem.

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The Declarative Paradigm

• A Decision Table is a tabular method for visualizing and specifying rules based on multiple factors.


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Prolog Facts

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Prolog Facts

• You can query a program’s database by asking a question, called a Goal.


The ?- prompt allows you to query a set of Prolog facts and rules.

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Prolog Facts

• Finding a value for a variable is referred to as Instantiation.


Prolog uses a process called instantiation tosatisfy goals.

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Prolog Rules

• The order of program instructions is critically important.


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Input Capabilities

When the pizza programruns, the pizzainfo rulecollects input for the prices, the sizes, and the shapes of two pizzas.

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Declarative Languages and Applications

• Declarative programming languages are most suitable for problems that pertain to words and concepts rather than to numbers.– Highly effective programming environment.– Not commonly used for production applications.– Minimal input and output capabilities.– Poor performance on today’s personal computer

architecture.


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Section E: Event Driven Programming

• A Visual Development Environment (VDE) provides programmers with tools to build substantial sections of a program.– Form design grid– Control– Properties– Event– Event-

handling code

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Program Coding (Event Driven)

Controls, such as theBest Deal button, can be selected by a programmer from a properties list.

Here a programmer is selecting the background color for the Best Deal button.

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Program Coding (Event Driven)

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Section F: Secure Programming

• Black Hat Exploits• Secure Software Development• Mitigation


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Black Hat Exploits

• Today’s operating systems, utilities, and application software are full of defects that create security holes, which are exploited by black hats.

• A buffer overflow (also called a buffer overrun) is a condition in which data in memory exceeds its expected boundaries and flows into memory areas intended for use by other data.


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Black Hat Exploits

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Black Hat Exploits

• Verbose error messages can also present attackers with information about the directory location of programs or files, the structure of a database, or the layout of the program in memory.


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Secure Software Development

• Most software security problems can be traced back to defects that programmers unintentionally introduce in software during design and development.

• Formal methods help programmers apply rigorous logical and mathematical models to software design, coding, testing, and verification.

• Threat modeling (risk analysis).


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• An attack tree is a hierarchical diagram of potential attacks against a system


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• Defensive programming (also referred to as secure programming) is an approach to software development in which programmers anticipate what might go wrong as their programs run and take steps to smoothly handle those situations.– Source code walkthroughs– Simplification– Filtering input

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• Signed code is a software program that identifies its source and carries a digital certificate attesting to its authenticity.

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Mitigation

• Despite defensive programming and other tactics to produce secure software, some defects inevitably remain undiscovered in products that end up in the consumers’ hands.

• When bugs are discovered, the programmer’s remaining line of defense is to produce a bug fix, or patch.


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Mitigation

• Take the following steps to avoid security problems that stem from software defects.– Select applications from software publishers with a good

security track record.– Watch for patches and apply them.– Consider using open source software, which has been

extensively reviewed by the programming community.– Keep your firewall and antivirus software deployed and up-

to-date.


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Section G: Structured Query Language (SQL)• SQL is the language for querying and updating

databases.• “universal” database language• Developed in the mid-1970’s by IBM• Original name SEQUEL changed to SQL in 1980.

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Plan Ahead for a Query

• Select the fields for the query• Determine which table or tables contain these fields• Determine criteria• Determine sort order• Determine grouping• Determine any update operations to be performed

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Creating a New SQL Query in Access2007 • Hide the Navigation Pane• Click Create on the Ribbon to display the Create tab• Click the Query Design button on the Create tab to

create a query• Close the Show Table dialog box without adding any

tables• Click the View button arrow to display the View menu• Click SQL View to view the query in SQL view

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Computer Programming and Database Handout

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