DBMS

Data

Stored representations of meaningful objects and events; raw unprocessed information that can be structured or unstructured.

Database

An organized collection of logically related data stored and accessed electronically.

Information

Data that has been processed to increase knowledge of a person using it.

Metadata

Data describing the properties and context of other data

Database Management System (DBMS)

Software used to create

Database System

Includes the database

Database Schema

Structure of the database defining how data is organized.

Table

Structure that holds related data.

Record

A row in a table representing a single data entry.

Field

A column in a table representing an attribute.

Key

Unique identifier for a record.

Program-Data Independence

Ability to change the schema without affecting application programs.

Data Redundancy

Unnecessary duplication of data in multiple locations.

Data Sharing

Improved access and sharing of data among users through centralized control.

Data Integrity

Accuracy and consistency of stored data.

Enterprise Resource Planning (ERP)

Integrates all enterprise functions like manufacturing

Data Warehouse

Integrated decision support system derived from operational databases.

Repository

Centralized storehouse of metadata.

CASE Tools

Computer-aided tools for software and database design.

End User

Person who uses database applications.

Data Modeling

Process of defining and organizing data structures for efficient management and retrieval.

Data Model

Abstract representation defining how data is structured and related.

Entity-Relationship (ER) Model

Visual tool showing entities

Normalization

Process of organizing data to minimize redundancy and dependency.

Relationship

Association between entities such as one-to-one or one-to-many.

Schema Design

Development of a conceptual schema based on business needs.

Business Rule

Statement defining or constraining business behavior.

Data Definition

Explanation of a term or fact with specific meaning.

Conceptual Data Model

High-level model describing data independent of DBMS; focuses on meaning and relationships.

Representational Data Model

Logical model showing data structure

Physical Data Model

Defines how data will be stored and accessed in a specific DBMS.

Relational Algebra

Procedural query language describing how to retrieve data.

Relational Calculus

Non-procedural query language describing what data to retrieve.

Multidimensional Model

Represents business data in terms of facts and dimensions for analysis (e.g.

Top-Down Modeling

Approach starting from high-level requirements down to database design.

Bottom-Up Modeling

Approach modifying existing databases starting from physical structures.

Entity Relationship Diagram (ERD)

Graphical representation of entities

Entity

Object or concept about which data is stored.

Strong Entity

Entity that exists independently and has its own unique identifier.

Weak Entity

Entity dependent on another for identification.

Associative Entity

Entity that arises from many-to-many relationships and holds attributes of the relationship.

Attribute

Characteristic or property of an entity or relationship.

Identifier (Key)

Attribute or set of attributes that uniquely identify entity instances.

Unary Relationship

Relationship within the same entity.

Binary Relationship

Relationship between two entities.

Ternary Relationship

Relationship involving three entities.

Cardinality

Defines the number of occurrences of one entity related to another.

Minimum Cardinality

Specifies whether a relationship is optional (0) or mandatory (1).

Maximum Cardinality

Specifies the maximum number of relationships (1 or many).

Primary Key

Unique identifier that cannot be null.

Foreign Key

Attribute linking one table to another.

Composite Attribute

Attribute made up of multiple parts (e.g.

Derived Attribute

Value calculated from other attributes (e.g.

Data Flow Diagram (DFD)

Visual model showing how data moves through a system.

System

Group of interrelated procedures for a specific business function.

Analysis

Process of breaking down a system into components.

Design

Process of constructing or creating a system plan.

Entity (DFD)

External data source or destination defining system boundaries.

Process

Transformation of data; shown as verb phrases.

Data Store

Resting place for data

Data Flow

Movement of data between processes

Context Diagram

High-level DFD showing system boundaries and major data flows.

Level 0 DFD

Expanded DFD showing major sub-processes.

Level 1 DFD

Further detailed breakdown of Level 0 processes.

Law of Conservation of Data

Data cannot be created or destroyed; it must move through processes.

SQL

Standard language for managing data in relational databases

Physical Level

Describes how data is stored on hardware.

Logical Level

Describes what data is stored and its relationships.

One (1:1) — Diagram: —|

One can have one of the other entity (min 1

Optional One (0 or 1) — Diagram: —O|

May have one related record or none (0 or 1). Example: A customer may have one loyalty card

Mandatory One (exactly 1) — Diagram: —||

Must have exactly one related relationship (1). Example: Each student must have exactly one ID card.

Many (0-n) — Diagram: —<

One can have many of the other entities (0-n). Example: A customer can place many orders.

Mandatory Many (1-n) — Diagram: —<|

Must have at least one or more related relationships (1-n). Example: Each department must have at least one employee.

Optional Many (0-n) — Diagram: —O<

May or may not have related records (0-n). Example: A teacher may have many advisees

• database is directly available to the user for using it to store data

• used for local application development, where programmers communicate directly with the database for quick response

2 tier DBMS

• includes and application layer between the user and the DBMS which is responsible between the user’s request with the DBMS

• application interface known as ODBC (Open Database Connectivity) provides an API that allow client-side program to call the DBMS

• provides extra security as DBMS is not exposed to the end user directly

3 tier DBMS

• most commonly used architecture for web applications

• an additional Presentation or GUI Layer is added, which provides a graphical user interface for the End user to interact with the DBMS

• for the end user, the GUI layer is the database system

• ex: mySQL’s PhpMyAdmin

Hierarchical data model

oldest model, tree like structure, implements 1:1 and 1:n relationship

network data model

organizes records to one another thru links/pointers, directed graphs are used, implements 1:1, 1:n, and n:n relationships

Relational data model

uses table to store records, and relationships between tables are set using common fields