Test 1 Note Cards Flashcards
The problems with lists are …
The Redundancy and Multiple themes
Addresses many of the information complexity issues …
Relational Databases
stores information in tables, each info topic is stored in its own table . ..
relational database
Aa international standard for creating, processing, and querying databases and their tables…
SQL
The four components of a database system are:
Users, Database Application, Database Management System (DBMS), Database
uses a database application to track things
user
a self-describing collection of related records
Database
contents of a Database are…
user data
Metadata
Indexes
Application Metadata
serves as an intermediary between database applications and the database…
Database Management System (DBMS)
ensure that the values of a column in one table are valid based on values in another table
referential integrity constraints
a set of one or more computer programs that serve as an intermediary between the user and this DBMS …
database application
Name the functions of a Database Applications
Create and process forms
Process User Queries
Create and process reports
Execute application logic
control database applications
An…… is important to auser that needs to be represented in a database, represents one theme or topic
entity
a……. is a 2-D table that has specific characteristics that consist of rows and columns
relation
Two characteristics of a Relation are ….
Cells of the table hold a single valve
No two rows may be identical
A…… is one or more columns of relations that are used to identify a row
Key
A key that contains two or more attributes, needed for a key to be unique,…
composite Key
is candidate to become a primary key…
Candidate key
chosen to be the main key for the relation. uniquely identifys a single row….
primary key
unique numeric value that is added to a relation to serve as the primary or main key.
surrogate key
a primary key from one table placed into another
foreign key
states that every value of a foreign key must match a value of an existing primary key…
referential integrity
means no data was entered
Null value
when one attribute determines the value of another attribute in the same table
functional Dependency
ensures that a relation is well formed
Normalization
Along with relationships These are the requirements of an E-R Model
- Entities
- Attributes
- Identifiers
a description of the structure and format of occurrences of the entity
entity class
an occurrence of an entity within an entity class
entity instance
describes the entity’s characteristics
attributes
identifies a particular instance in the entity class…
identifiers
Make an entity Attribute Display
Entity
Identifires
attriutes
defines the numbers of entity classes participating in the relationship
relationship degree
one entity related to another one
1:1
one entity related many entities
1:N
Many entities related to many entities
N:M
relationships are named and classified by their …, which also means count
cardinality
maximun number at entity Instances that may participate in a relationship.
Maxium cardinality
zero optionaI and one mandatory …
Minimum cardinality
a company has an employee represents a…..
HAS- A relationship
Uses Crow’s feet to show the many sides of a relationship
Information Engineering
crowfoot model
a version of the E-M model that is a national standard….
IDEF1X
a set of structures and techniques for modeling and designing objet - oriented programs and applications
UML
an entity that can not exist in the database without another entity
weak entity
an entity that is not weak
strong entity
relationship between a strong and weak entity is called an……. if the weak entity is ID- dependent
identifying relationship
relationship between a strong and weak entity is called an……. if the weak entity is non ID-dependent
non identifying relationship
if the supertype relates to at most one subtype, then it is
exclusive
if the supertype relates to one or more subtypes, then it is
inclusive
attributes of a supertype are called
discriminator
relationships that connect supertypes and subtypes are called
IS-A relationships
a…… is when an entity has a relationship to itself
recursive relationship
