RDBMS and SQL Fundamentals

Relational Database Management System (RDBMS) Overview

• RDBMS refers to software systems used to manage databases.
• RDBMS facilitates the creation, maintenance, and controlled access to relational databases.
• Relational databases utilize a relational data model, storing data in two-dimensional tables.
• Tables consist of columns/fields and rows/records.
• Columns are attributes (data values), and rows are tuples (records).
• Databases contain tables that maintain records.
• Attributes describe entity instances, e.g., a student with attributes like ID, name, age, grade level, and sex.
• Each field in a table requires a name and data type.
• Data types specify the kind of data to be stored in a field, such as a four-digit number for a residence ID.

SQL for Database Manipulation

• SQL (Structured Query Language) is a standard language used to access and manipulate databases.
• It's designed for interacting with relational databases like Microsoft Access.
• SQL includes commands for various database operations, categorized as follows:
  • Data Definition Language (DDL) provides commands to create/modify tables and establish relationships.
  • Data Manipulation Language (DML) provides commands to manage data through inserting, updating, deleting, and navigating.
  • Data Query Language (DQL) is used to query or select data subsets.
• Relational databases store data in tables that relate to each other using Primary Keys (PK) and Foreign Keys (FK).
• Tables are two-dimensional grids with rows and columns.
• Rows (records) are horizontal, while columns (fields) are vertical.
• A table can hold extensive information, potentially thousands of rows.
• Data operations begin and end with tables, representing all data within tables.
• Tables can only have a single primary key, even if consisting of several columns.
• RDBMS like MySQL, Informix, Oracle, MS Access, and SQL Server utilize SQL as their standard language.
• SQL is not case sensitive.
• SQL commands are instructions used to communicate with the database, performing specific tasks, functions, and queries.
• SQL functions include:
  • Executing queries.
  • Retrieving data.
  • Inserting records.
  • Updating records.
  • Deleting records.
  • Creating databases and tables.
  • Creating stored procedures and views.

Database vs. Application vs. Management System

• A database is a structured collection of integrated records, essentially organized data.
• A database application is a program that operates on a database, enabling users to maintain and query it.
• A database management system (DBMS) controls database access; applications work through a DBMS to access the database.

Introduction to XML

• XML is Extensible Markup Language.
• XML is a text-based markup language used for storing and transporting data via standard Internet protocols.
• XML tags differ from HTML tags in that they aren't predefined.
• XML-element names are case-sensitive, requiring matching start and end tag cases.
• XML documents can contain only one root element that branches to child elements.
• XML elements require a closing tag.

Software Installation

• Installation is the process of preparing a program to run, including configuring hardware and software.
• A device driver is a program that controls a specific hardware device.

Software Troubleshooting

• Troubleshooting is a systematic approach to finding and identifying the causes of faults in a computer system.

Tools to Speed Up Computer System

• Tools include:
  • Disk defragmenter tool: rearranges files to reduce fragmentation and improve performance.
  • Disk cleanup tool: deletes unused files to free disk space.
  • Windows update: ensures the computer is up-to-date with features and security.
  • System Restore: creates restore points or restores the system to a previous state to resolve malfunctions.

Network Troubleshooting

• Networks connect computers to share resources and enable electronic communication.
• Connections can be made by cables, phone lines, radio waves, satellites, or laser beams.
• Network troubleshooting involves techniques and procedures used to locate, analyze, and fix network issues.
• Network troubleshooting involves techniques and procedures used to locate, analyze, and fix network issues.

Basic Network Problems

• Network problems are:
  • Cable Problem: faulty, shortened, or damaged.
  • Connectivity Problem: Port or interface issues preventing host communication.
  • Out of Reach Issue: Wireless host too far from the access point, or obstacles present.
  • Configuration Issue: Incorrect configurations lead to network faults.
  • Software Issue: Compatibility issues and version mismatch interrupting IP data transmission.
  • Traffic overload: Device capacity exceeded, causing abnormal behavior.

Network Maintenance Tools

• Tools include:
  • Wire Crimpers: attaches media connectors to cable ends to make/modify network cables.
  • Cable Testers: Verifys signal transmissions to find out whether the cables in network are functioning properly when diagnosing connectivity issues.
  • Punch Down Tool: connects cable wires to a patch panel or block in wiring closets.
  • Tone Generator: sends electrical signals through UTP wires to verify wire connectivity.
  • Multimeter: measures electrical properties like voltage, current, and resistance for troubleshooting.