Ch. 4 Relational Databases and Enterprise Systems

Database Concepts

• A database is a collection of logically related data used for various purposes.
• Hierarchical data models structure data in a tree format, enabling a 1:N (one to many) relationship through defined parent/child connections.
• Network data model allows complex relationships by supporting many-to-many associations among objects.

Relational Database

• The relational data model organizes data into two-dimensional tables, significantly reducing information redundancy and is widely used due to its flexibility and scalability.
• A database management system (DBMS) is a program for creating, modifying, and querying databases, facilitating efficient storage and retrieval of information.

Key Database Elements

• A data dictionary outlines characteristics of each database field, including descriptions, lengths, and types.
• A database administrator oversees the database's design, implementation, maintenance, and security.
• Attributes are properties that describe the classes in a database.

Keys in Databases

• The primary key is a unique identifier for each row in a table, with the first attribute marked with a key symbol in Microsoft Access.
• A foreign key links two tables together, representing the primary key from another table, crucial for establishing many-to-many relationships.
• Entity integrity rule mandates that a primary key should not contain null values.
• Referential integrity rule states that a foreign key must match a primary key from the corresponding table or be null.

Database Structure

• The table is the fundamental structure within a database.
• A query retrieves and displays data from records, answering specific questions or calculations.
• Forms help users input data into tables and view existing records, while reports compile integrated data for decision-making without allowing edits.

Data Management Tools

• Pages enable real-time data entry from outside the database system.
• Macros automate repetitive tasks or processes defined by users.
• Modules allow alterations to Access's underlying code and can include built-in features.

Query Language

• Structured Query Language (SQL) is designed for data retrieval from relational databases, based on principles of relational algebra.

Enterprise Systems

• An enterprise system (ES) centralizes data collection from various organizational departments, integrating and automating critical business processes across the value chain.
• Major ES vendors include SAP, Oracle, and Microsoft, offering integrated software solutions that utilize the relational data model with primary and foreign keys.

Database Design and Functionality

• A class in a relational database typically represents a person, place, thing, transaction, or event with stored information.
• Valid primary keys for various tables ensure each record's uniqueness (e.g., cash receipt number for cash receipt tables).
• In SQL, the FROM clause specifies tables for data retrieval, while the WHERE clause sets criteria for displayed results. The ORDER clause determines which columns to sort, and "Order by ASC" indicates ascending order.

Cloud Computing

• Cloud computing refers to internet-based resources where software and information are shared and accessed on demand.

Example Attributes

• Customer attributes might include Customer ID, last name, and address, while sales attributes could encompass Invoice number, Customer number, and Salesperson ID.
• SAP offers various modules for implementation such as Financial Accounting, Payroll, and Sales and Distribution.

Test your knowledge of key concepts from Chapter 4 on Relational Databases and Enterprise Systems. This quiz covers definitions and models like database structures and data relationships. Perfect for reinforcing your understanding of database fundamentals.