Notes, summaries, assignments, exams, and problems for Computer science

Essential Database Field Properties

• Validation Rule and Validation Text: This is a standard that all data in a field must meet. If data is entered that does not meet this standard, the tables will not be updated correctly. The Validation Text is the message that appears on the screen when you enter a figure that does not meet the validation rule; this message reports the specific error being committed.
• Required: This option lets you choose whether the field will be mandatory. If you select "Yes," you cannot leave this field blank, and the table is blocked until it is filled.
• Input Mask: This sets the default format that the data will take automatically. We use 0 for numbers and L for letters. Example: 91 881 14 000 00 00 79/00
• Indexed: This lets

Software Classification

We can classify software into three types:

• Operating Systems: Manage computer resources.
• Programming Languages: Used to build applications (e.g., Java, C++, Assembly).
• Applications and Programs: Perform specific operations.

Programming Languages

What are Programming Languages?

Programming languages are established systems of communication understood by both programmers and machines, used to develop programs. They are constantly evolving, with many based on English, but increasingly visual and intuitive.

Word Processors

What is a Word Processor?

Word processors offer more than just writing; they allow for the inclusion of photos and drawings, text justification and formatting, spell checking, and integration with other applications....

Key Computer and Software Terms

1. Text Editor: It is a program through which we can enter text without a specific file format.

2. Word Processing: It serves not only to write, but also to format the text and offer a better appearance.

3. Document: A data file with a specific format that is interpreted by the processor.

4. Book: An entire document with all its pages.

5. Section: An organizational unit of the document that may implement a number of characteristics.

6. Paragraph: An organizational unit below a section.

7. Style: A way of sorting, identifying, and storing a set of formatting and other features.

8. Index: A part of the document, usually found at the end.

9. Table of Contents: An index with page layout format which summarizes the contents...

Database Management System (DBMS) Functions

A DBMS is a set of programs that provide access to data. Its primary functions include:

Core DBMS Capabilities

1. Facilitate Data Access: Enables easy access to data, including graphical representations.
2. Data Consistency and Integrity:
   • Consistency: Ensures any change respects the database integrity rules.
   • Integrity: Enforces restrictions (e.g., Laboral Age > 16).
   • Registration: Prevents duplicate entries (e.g., student not repeated).
   • Table Constraints: Limits on table size (e.g., N students per group < 35).
   • Relationships: Ensures referential integrity (e.g., a producer must have a valid vendor code existing in the suppliers table).
3. Database Security:
   • Making and retrieving Backups.
   • Reaction to system failures.

Data

Data is the collection of facts considered in isolation. It describes an organization and carries meaning, but generally is not useful by itself.

Information

Information is data that has been manipulated and is useful to someone. Information must have value; otherwise, it would be considered just data. Information tells people something that confirms what they knew or suspected. (What, who, and when?)

Why? Because telecommunication networks transmit data, the networks do not identify meanings (information). The objective of networking is to take data from one place to another.

Data Types

• Analog: Continuous
• Digital: Discrete

Symbols limited by their use and origin:

• Alphanumeric
• Graphic
• Image
• Audio
• Video
• Multimedia

Model of a Basic Communication System

Components:...

Technical Design of Systems

At the end of this activity, the following items are obtained:

• Modular design of the system.
• Description of interfaces between system modules.
• Description of interfaces to other system modules.
• Definition of the user interface.
• Description of system components.

Structured Programming Techniques

Data Entry:

This part of the program consists of instructions that take information from an input/output device and transfer it to main memory for further processing.

Process or Algorithm:

The set of instructions that process the input data to obtain new information.

Output Results:

This consists of instructions that send the results of a process to an input/output device.

System Technology Environment: Objectives

The objectives include:...

Secure Sockets Layer (SSL)

Secure Sockets Layer (SSL) is most often used to encrypt information on the Internet. It is a protocol that encrypts database (DB) connections by selecting an encryption method and generating the necessary keys for the entire session.

How SSL Works

1. The browser requests a page from a secure server. The request is identified by the HTTPS protocol.
2. They agree on algorithms that ensure confidentiality, integrity, and authenticity.
3. The server sends the browser its standard X509 certificate containing its public key. If the application requires it, it in turn requests the client's certificate.
4. The browser sends the server a master key from which it generates the session key to encrypt data to be exchanged.
5. Finally, it checks the