Course 4: Introduction to Relational Databases (RDBMS) Flashcards
information model
abstract, formal representation of entities that includes their properties, relationships and the operations that can be performed on them
data models
concrete, specific and include details
hierarchal data model
organizes its data using tree structure with root of the tree being parent and followed by child nodes
relational data model
most used model. data stored in tables, providing logical data independence, physical data independence, and physical storage independence
entities
noun such as a person, place, or thing and represented by rectangle in ER diagram
attributes
properties or characteristics of an entity
relationship sets
represented by diamonds with lines connecting associated entities to show relationship and whether one-to-one, one-to-many, or many-to-many relationship
relation
another term for table
relation instance
table made up of rows and columns
degree
number of attributes (columns) in a relation
cardinality
number of tuples (rows)
single-tier database architecture
database resides on user’s system and access is often limited to a single user. useful for dev or testing or when database is embedded in a local application
client-server (2-tier) database architecture
resides on a remote server and users access it from client systems often through web page or local app. used for multi-user scenarios and typical for production environments
cloud database architecture
easy for users to access and dont have to maintain support infrastructure. client apps and users typically access through an application server layer or interface in the cloud. flexible and used for dev, testing, and full production environments
layers of a database management system software
1 data access layer
2 database engine layer
3 database storage layer
4 data access layer