Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
21 Cards in this Set
- Front
- Back
|
What is information-level design?
|
independent of dbms implementation
|
|
|
Whats a physical lvl design?
|
information lvl design adapted for specific dbms
|
|
|
Whats a user view?
|
Set of requirements to support a particular user
|
|
|
Whats a cumulative design
|
collection of all the user views
|
|
|
Steps for information lvl design?
|
represent user view as a collection of tables, normalize these tables. identify primary keys, merge these tables w/ the cumulative design
|
|
|
How do you make a one to many relationship. (and one to one)
|
put the primary key of the one entity into the other table as the foreign key.
|
|
|
How do you make a many to many relationship?
|
create a new table whose primary key is the combination of keys of the original tables
|
|
|
Alternate key
|
key that could have been chosen as primary key
|
|
|
secondary key
|
columns of interest strictly for retrieval
|
|
|
foreign key
|
key that must match the primary key values of the corresponding row in a specified table
|
|
|
natural key
|
column that uniquely identifies entity
|
|
|
artificial key
|
column that is created to serve as primary key
|
|
|
DBDL
|
database design language
|
|
|
ER Diagrams
|
represent the structure of the db visually
|
|
|
bottom up design
|
start with user requirements and work your way up.
|
|
|
top down design
|
start with general db design and refine until all requirements are met
|
|
|
Null
|
absence of a value in a field. Null fields can be avoided by splitting tables
|
|
|
composite entity
|
exists to implement a many to many relationship
|
|
|
existence dependency
|
existence of one entity depends on the existence of another
|
|
|
weak entity
|
depends on another entity for its existence.
|
|
|
cardinality
|
number of items that must be included in a relationship
|
