DATA DESIGN Flashcards
Describe data structures
A data structure is a framework for organizing, storing, and managing data
Data structures consist of files or tables that interact in various ways
Each file or table contains data about people, places,
things, or events
What are the different modes of data design
File-oriented systems/file processing systems
-They store data in separate files that are not connected or linked
-Redundancy is a major disadvantage of file-oriented
systems because it threatens data quality and integrity
A DBMS/Relational DB/Relational model
-Has two or more separate tables that are joined, so
they act like one large table
-A common field is then used to connect the tables
-Continues to be the dominant approach for organizing,
storing, and managing business data
Describe the web based design and why it is so attractive
In a web-based design, the Internet serves as the front end/interface for the DBMS
Internet technology provides enormous power
and flexibility because the related information system is not tied to any specific combination of hardware and software
Access to the database requires only a web browser and an Internet connection
Web-based systems are popular because they offer ease of access, cost-effectiveness, and worldwide connectivity - all of which are vital to companies that must compete in a global economy
How does middleware play into web-based design
It is necessary to use middleware, which is a software that integrates different applications and allows them to exchange data
Middleware can interprets client requests in HTML form and translates the requests into commands that the database can execute
Describe the following terms: entity, table, field and record
An entity is a person, a place, a thing, or an event for
which data is collected and maintained
A table/file contains a set of related records that store
data about a specific entity
A field/attribute is a single characteristic or fact about
an entity
A record/tuple is a set of related fields that describes
one instance, or occurrence, of an entity, such as one
customer, one order, or one product
Describe an ERD
An entity-relationship diagram (ERD) is a model that shows the logical relationships and interaction among
system entities
An ERD provides an overall view of the system and a blueprint for creating the physical data structures
Important tips when drawing an ERD
Entities are represented as rectangles and relationships as diamond shapes
The entity rectangles are labeled with singular nouns, and the relationship diamonds are labeled with verbs,
usually in a top-bottom and left-to-right fashion
Describe and illustrate the different types of relationships
A one-to-one relationship, abbreviated 1: 1, exists when exactly one of the second entity occurs for each instance of the first entity. A number 1 is placed alongside each of the two connecting lines to indicate
A one-to-many relationship, abbreviated 1:M, exists when one occurrence of the first entity can relate to many instances of the second entity, but each instance
of the second entity can associate with only one instance of the first entity. The line connecting the many entity is labeled with the letter M and the number 1 labels the other connecting line
A many-to-many relationship, abbreviated M:N, exists when one instance of the first entity can
relate to many instances of the second entity, and one instance of the second entity can relate to many instances of the first entity. One of the connecting lines is labeled with the letter M, and the letter N labels the other connection
-The event or transaction that links the two entities is actually a third entity, called an associative entity, that has its own characteristics
Describe cardinality
Cardinality describes the numeric relationship between two entities and shows how instances of one entity relate to instances of another entity
Cardinality notation uses special symbols to represent the relationship
