COMP281

Define data dictionary

A data dictionary provides a detailed description of all tables in the database

What a database is

A database is a shared, integrated computer structure that houses a collection of related data. Databases contain end-user data (raw facts) and metadata (data about data).

Components of database systems

A database system consists of logically related data stored in a single data repository.

How relations are organized into tables with rows and columns

A relation is also known as a table which contains rows, or tuples, and columns, or attributes.

Define system catalog

A system catalog is described as a detail data dictionary that describes all objects in the database.

Business rules and how they influence database design

Business rules are brief, precise, descriptions of a policy, procedure, or principle within an organization. They are used to define entities, attributes, relationships, and constraints.

Defining and refining relationships between entities and incorporating into database design process

Business rules are used to define the relationships between entities in a database

Reconciliation of conflicting goals in database design

Conflicting goals include design standards, processing speed, and information requirements. It is important to reach all logical requirements.

Main functions/components of a DBMS

DBMS manage data dictionaries, data storage, data transformation and presentation, security management, multiuser access control, backup and recovery management, data integrity management, SQL access, database communication interfaces.

Difference between data and information

Data is just raw facts that has not been put to meaningful use. Information is the result of processing data to reveal its meaning.

Why data models are important

Data models are a communication tool that facilitate communication between the designer, application programmer, and end user. They can also improve understanding of the organization.

How the major data models evolved and what they are

Data models have evolved to try to overcoming the shortcomings of earlier models. They are hierarchical model, network model, the relational model, the entity relationship model, the object oriented model, the object/relational model, and NoSQL.

How to handle data redundancy in an RDBMS

Data redundancy is handled by using common attributes that are shared by tables, called foreign keys.

Classifying data models by level of abstraction

Database design starts at a high level of abstraction and details are added as the design comes closer to implementation. The hierarchical model has a low level of abstraction followed by the network model, the relational model, the OO model, and the ER model (high).

Why they are valuable assets

Databases allow users to collect raw data and process that data into meaningful information for business planning and analysis.

Different types of databases

Databases can be classified by the number of users (single-user database, multiuser database), by location (centralized database, distributed database), by the type of data stored in them (general-purpose or discipline-specific database), or most commonly by how they will be used (operational, online transaction processing (OTP), production databases or analytical databases)

Main characteristics of entity relationship components

Entities (nouns) refer to a table in the database, relationships are associations between entities , and attributes (table columns) are characteristics of the entity

Basic building blocks of data models

Entities, attributes, relationships, and constraints

Importance of database design

Even a good DBMS will perform poorly with a badly designed database. Having a good design ensures accurate results and can provide valuable information to an organization.

How modern databases evolved from file systems

File systems contain large amount of unrelated and often redundant information that was difficult to generate meaning information from. Databases eliminate data inconsistencies and anomalies while showing meaningful relationship between the data.

Components of file systems

File systems evolved from pen and paper files to computerized files as the need to store data increased. Computerized file systems resemble manual file systems but allowed for data to be processed into meaningful information, however, this still required extensive programming and could take long periods of time to generate reports.

Flaws in file systems

Hard to get valuable information from. Difficult to manage. Requires extensive programming to make changes. Lacks security.

Importance of indexing

Indexes are used to retrieve data more efficiently.

The relational database operators

SELECT, PROJECT, UNION, INTERSECT, DIFFERENCE, PRODUCT, JOIN, and DIVIDE

How the relational model takes a logical view of data

The relational model allows users to manipulate data in a way that seems logical by establishing relationships between entities in tables throughout the database.