Notes, summaries, assignments, exams, and problems for Computers

Starting a Session and Destroying Variables (inicio.php)

session_start();
unset($_SESSION["host"]);

Creating a Session and Attempting a Connection (marco.php)

session_start();
$conn = @mysql_connect($host, $user, $password) or die("Incorrect user or password");
@mysql_select_db($db, $conn) or die("Cannot open the DB");

Assigning Connection Parameters to Session Variables

$_SESSION["host"] = $host;
$_SESSION['User'] = $user;

Starting a Session, Connecting to the Database, and Sending an Insertion Query (altas.php)

<?
 session_start();
 $conn = mysql_connect($host, $user, $password) or die("Incorrect user or password");
 mysql_select_db($db, $conn) or die("Not selected");
 $query = "insert into departments values ($dep, '$nom', '$crazy')";
 $result

Database Fundamentals

A database is a set of tools designed to manage information related to a specific topic, such as books or CDs.

Core Database Components

• Tables

  Tables store data in an organized manner, featuring fields that allow information to be handled effectively.

• Queries

  Queries are tools that provide answers to questions that may arise about the stored data.

• Forms

  Forms are data objects that present information differently from a table, offering a more pleasant, colorful, and effective user interface.

• Reports

  Reports allow you to print stored data in formats designed by the user.

Understanding Data Types

Data types define the kind of values a field can hold. Here are common data types:

• Text (VARCHAR)

  Can be formed by letters, numbers, and spaces,

Disk Quota Management in Windows Server 2008

Windows Server 2008 offers two distinct types of disk quotas to help manage storage utilization:

• NTFS Disk Quotas

  Available in all versions of Windows Server 2008, NTFS Disk Quotas allow administrators to manage the disk space used by users. Quotas are set for each volume. While users receive warning messages when exceeding their quota, event logging is the primary communication channel for disk quota management.

• File Server Resource Manager (FSRM)

  Windows Server 2008 supports File Server Resource Manager (FSRM) for advanced quota management. FSRM enables the management of space utilization for specific folders and volumes. Users approaching or exceeding their limits will automatically receive email notifications.

Features of Free Software

Free software provides the following freedoms:

• The freedom to run the program for any purpose.
• The freedom to study how the program works and adapt it to your needs.
• The freedom to redistribute copies so you can help others.
• The freedom to improve the program and release improvements to the public, so that the whole community benefits.

Sharing Resources in Windows

To share network resources in Windows, you need to ensure that file and printer sharing is enabled in the local area network configuration. To do this, go to "Network Connections", right-click on "Local Area Connection", and select "Properties".

Types of Users

• Administrator or Root: Responsible for configuration and maintenance.
• User: Uses the system and accesses resources

Processor Front

The processor front involves three components: source, destination, and message. The source (e.g., a terminal or computer) sends a message. The destination (e.g., another terminal or computer) receives the message. The front-end processor acts as the connection between the source and destination, managing the message transfer. It frees the host processor from communication tasks, handling message routing, transmission monitoring, code translation, and encryption. All data transmitted to or from the host processor are managed through this specialized front-end processor, allowing the host processor to operate more efficiently and focus on application processing.

Types of Communications

A network enables computer connections to share... Continue reading "Computer Network Communications" »

Software Development Models

Attributes of Effective Requirements (AtrERS): Correct, unambiguous, complete, verifiable, consistent, modifiable, concise, organized, searchable, understandable by the client, regardless of design.

Scaling Factors: Correctness, reliability, efficiency, integrity, ease of use and maintenance, flexibility, ease of testing, portability, reusability, ease of interoperation.

Life History: Succession of stages through which a software product passes during its existence. Attempts to determine the order of the steps involved and the criteria associated with the transition between these stages.

Software Engineering: Application of scientific knowledge to the design and construction of computer programs and associated documentation... Continue reading "Software Development Models: Waterfall, Prototype, and More" »

Advanced Features

Advanced features facilitate consultation similar to a spreadsheet because they work based on rows and columns.

• COUNT(): Count the number of rows in the column set
• MIN(): Find the minimum value of the column set
• MAX(): Find the maximum value of the column set
• AVG(): Gets the average values in the column set
• SUM(): Gets the total value implied by the values obtained in the column provided

Modifying the Database

SQL DDL has modules for the definition of data that allows us to create or modify table structure.

The instructions for these operations are:

• CREATE TABLE: Allows you to create an empty data table.
• INSERT: Allows you to store records in a table created.
• UPDATE: You can modify data records stored in the table.
• DELETE: Deletes a record

Access 2000 Queries: Fundamentals

Access 2000 is not case-sensitive when searching for records.

Saving a Query

1. To save the query, click the Save button in the dialog box. A prompt will appear to name the query.
2. Enter the name of the query.
3. Click the OK button.
4. To close the query, click the Close button.

Running a Query

Queries can be run from the Query Design window or directly from the database window.

From the Database Window:

1. Select the query to execute.
2. Click the Open button.

From the Query Design Window:

1. Click the Run button on the toolbar.

When viewing query results, you are seeing a subset of the table that meets the specified criteria. Therefore, any data modification made here will also be applied to the related table.

Modifying Query Design

1. Navigate

System Calls: Core OS Interaction

A system call is the mechanism used by an application program to request a service from the operating system.

How a System Call is Made

When a call is made, it involves placing a set of parameters in a specific memory location and then executing a machine language instruction for the processor.

Common POSIX System Calls

In operating systems, common POSIX system calls include: open, read, write, close, wait, exec, fork, exit, and kill.

Understanding Processes

A process is an abstraction of a running program, also referred to as a task.

Process Model Properties

1. All software executables are organized into several sequential processes.
2. A process includes the running program, the current values of the program counter, registers,

Core Concepts of Artificial Intelligence

Defining Key AI Components

• Artificial Intelligence (AI): A study to perceive, reason, and act. Systems that think like humans, trying to understand how the human mind works. Systems based on rules.
• Intelligent Agent: An entity capable of perceiving its environment, processing these perceptions, and responding or acting in that environment rationally and appropriately.
• Prolog: A functional programming language based on logic.
• Rational Agent: Agent = Architecture + Program. The program depends on the environment in which it operates.

Types of Intelligent Agents and Programs

The agent program dictates how the agent chooses its actions:

1. Simple Reflex Agent

   Actions depend solely on the current perception and predefined