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42 Cards in this Set

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Why was file processing as a data system discarded?
1-Data was hard to get to
2-Data was duplicated
3-Application dependent
4-Couldn't change to newer/different systems(mac-win-unix)
A true Database consists of: (4)
1-integrated data
2-reduced data duplication
3-application independent
4-easy representation of the users reality
DBMS contains: (4)
1-Metadata / data definition / data dictionary
2-index
3-program
4-application metadata such as reports, forms, queries
Data Modeling
Process of creating a logical representation of the structure of the database
Entity Relationship consists of:(4)
Entities
Attributes
Identifier
Relationship
What is an entity
An object that the user wants to track, usually a noun, ie EMPLOYEE
Entity classes
Entities of a given type
Identifier
Uniquely identifies a row in a table
relationship
how entities are related:
one to one
one to many
many to many
Unified Modeling Language
Set of structures and techniques for modeling that includes information about object constraints and methods.
Attribute
Specifies what details are collected for each object.
Simple Attribute
a single data element
Group attribute
composite of related attributes such a address (no. and street)
Semantic Object Attribute
Object link-links back to a class
Semantic Object Attribute
Object link-links back to a class
Top Down Design uses what data model
E-R Diagram
Bottom up design uses what model?
SOM
What is a domain?
Set of values that a column may have
What is Normalization
The process of eliminating duplicating data.
Rows contain
relationships or tuples
columns contain
attributes
1NF
a relation must have only single-valued attributes
neither repeating groups nor arrays are permitted
2NF
Must be in 1nf and each non key attribute must be dependent on the whole key (might have composite keys)
3NF
Must be in 2NF
No transitive dependencies may exist
Transitive dependency
an attribute is dependent on another key, ie total price (qty x price)
BCNF
Must be in 3NF
Every determinant must be a candidate key
4NF
Must be a BCNF
May not contain multi-valued dependencies
1NF
2NF
3NF
BCNF
4NF
1NF-any relationship
2NF-all nonkey attributes are dependent on the entire key
3NF-no transitive dependencies
BCNF-every determinant is a candidate key

4NF
What are the 4 common relationship patterns?
1-tree
2-simple networks
3-complex networks
4-bills of materials
Tree relationship - cardinality?
hierarchy
1:N
Simple network - cardinality?
Only 1 : N
Complex Network -cardinality
has at least a N : M relationship
Bills of Materials - relationship pattern?
Parent relations are viewed as composites of the child relations--viewed from the bottom up.
null value
an attribute that has never been supplied.
Cardinality-max and min
indicates the max number of instances involved in a relationship

Min-indicates optional (0) or mandatory (1) relationship
Data Integrity
Stored logically consistent. Not duplicated in multiple tables
Moor's Law
Information doubles every 18 months and prices halves during the same time.
What is business rules?
Constrictions on business activities that must show up in the Database.
What is the difference between a class and an instance?
Class-Naming convention-DEPARTMENT
Instance-an occurance-ehs
A surrogate key
A number or code to give meaning to the information attached (autonumber)
surrogate key
ID's that have no real meaning other than to be a unique key
Attributes
Describes a characteristic of an entity, ie. employee name, employee ID, color,