Essential Concepts in Database Management, E-Commerce, and BI
Database Management Systems
DBMS Software Components
A Database Management System (DBMS) contains five important software components. One of these is the: Data Definition Subsystem.
Primary and Foreign Keys
Every primary key can also be used as a: Foreign Key (when referencing another table).
Storing Facts About Information (Metadata)
If you needed to store facts about the information you were collecting, you would use a: Data Dictionary.
Unique Identification Field
If your phone number was used in a clothing
Korn Shell Scripting, Linux Features, and Editor Basics
Korn Shell Relational Expressions
In Korn shell (and other Bourne-like shells), relational expressions are typically evaluated inside the [[ ... ]] (conditional) construct or using the test (or [) command. The operators use mnemonics for numerical comparison.
1. Numerical Comparisons in Korn Shell
(a) c ≥ d
To check if the numerical value of variable c is greater than or equal to the numerical value of variable d:
[[ $c -ge $d ]]The -ge operator stands for “greater than or equal to”.
(b) c < d
To
Read MoreHybrid Hash-Join Performance Optimization in Database Systems
Hybrid Hash-Join: Conceptual Explanation
Hybrid Hash-Join is an improved version of the standard Hash-Join algorithm that reduces disk I/O by using memory more efficiently during the join operation. It is particularly useful when:
- The build relation is larger than memory.
- Memory is still large enough to hold one or more partitions fully.
Why Use Hybrid Hash-Join?
In a normal Hash-Join:
- All partitions of the build relation are written to disk first.
- They are then read again for probing.
Hybrid Hash-Join
Read MoreFundamentals of DBMS and Database Concepts
Data, Information, Knowledge
Data – a fact that can be recorded or stored, e.g., person name, age, gender, weight, etc. Information – when data is processed, organized, structured, or presented in a given context so as to make it useful, it is called information. Knowledge – it is the appropriate collection of information.
DBMS (Database Management System)
DBMS = Database + Set of programs.
- Database – a collection of logically related data; e.g., books database in a library, student database in a university.
Essential Concepts in Information Technology and Digital Business
Core IT Fundamentals
Triple Convergence in IT
Content, devices, and sectors.
Information System Functions
- Obtain
- Process
- Store
- Distribute
Network Protocols and Addressing
Key Network Protocols Explained
- How to connect different devices? IP Protocol
- How to manage the exchange of information? TCP Protocol
- How to provide services? TCP/IP Protocol
- How to surf the Net? HTTP, HTML, etc.
IP Address Functions
IP addresses serve two principal functions:
- Host or network interface identification
- Location addressing
Software
Read MoreStructure of the Telephone User Network
Sections of the User Network
The user network is divided into three main parts: the main network, the distribution network, and the dispersion network.
The user network encompasses the path from the central plant’s main distribution point until the connection reaches the user’s telephone equipment. These stages are:
- Outdoor Line: This section covers the path from the central terminal to the distribution box. This connection typically uses high-capacity cables. The outdoor line is further divided into