Week 2 Flashcards
The diagram that identifies the entities in the database and shows how they are related (logical representation) is called what?
E-R Model (Entity-relationship model)
What are the 3 relationship types in a database?
One-to-One
One-to-Many
Many-to-Many
Why is database normalization used?
To reduce/eliminate data redundancy and avoid anomalies
This identifies each record
Primary Key
When more than 1 field is needed to uniquely identify a record, what type of key is used?
A composite primary key
When a composite primary key is used, but a record only depends on part of the primary key, what occurs?
Partial dependency
When at least 1 value in a record isn’t dependent on the primary key, but on a different field, it is what?
Transitive dependency
What does the 1NF in normalization do?
eliminates all repeating values and identifies a primary or primary composite key
What does the 2NF in normaliztion do?
Makes sure the table is in 1NF and eliminates partial dependencies
What does the 3NF in normaliztion do?
Makes sure the table is in 2NF and removes any transitive dependencies
This key is used to establish a relationship between tables and is a primary key in one of the tables. It’s usually on the many side of a relationship.
Foreign Key
Since many-to-many relationships can’t exist in a relational database, a _____ is used to create two one-to-many relationships.
bridging entity
A table that references the foreign key to show what a particular value is.
Lookup table
This is the language used to create database objects and manipulate data stored in a database.
Structured Query Language (SQL)
What is the difference between a query and a transaction?
Query- causes data to be retrieved
Transaction- causes data to to read and written (updating, creating, deleting objects)
The ability to change the structure of the data without having to change the program to access the data is called what?
program-data independence
The ability to change an operation in the data without having to change the interface used to process the operation is called what?
program-operation independence
A ___ is the difference perspectives that different users need to see the data.
View
An ____ is based on tree data structures or hash data structures that are suitably modified for disk search.
Index
When every A record must be related to a B record, it is called what?
(A section record must be related to a course record)
Referential integrity
Rules or definitions for the data in a database.
Integrity constraint
A collection of concepts that is used to describe the database structure (data types, relationships, constraints, etc) is called what?
Data model
An ___ represents a real-world concept or object.
Entity
Data that further describes an entity.
Attribute
What data is in the database at a given point in time.
Database state, instance.
