261_review Flashcards
Concept of database and database management systems
DB=an integrated collection of stored data that is centrally mannaged and controlled. Mgm-system software that manages and controls access tdb
What is a relational database system (RDBMS)?
a db mgm system that stores data in tables
Schema
a description of the structure-content-and access controls of a physical data store or database
Table
2D data structure containing rows and columns alscalled a relation
Row
portion of table containing data that describes one entity-relationship or object-alscalled tuple or record
Column/field
a column of a relational database table alscalled an attribute
Primary key
a key used tuniquely identify a row of a relation db table
Foreign key
a field value stored in one relational db table that alsexists as a primary key value in another table
Representing relationship
are represented within a relatikon db by foreign keys
Enforcing referential integrity
a consistent relational db state in which every foreign key value alsexists as a primary key value
Normalization
a technique that ensures relational db schema quality by minimizing data redundancy
Functional dependency
a 1-1 correspondence between 2 field values
1NF
a relational db table structure that has nrepeating fields or groups of fields
2NF
a relational db table structure in which every non-key field is functionally dependent on the primary key
3NF
a relational db table structure in which nnon-key field is functionally dependent on any other non-key field
Distributed Databases Architecture
organizations typically store data in many different databases-often under the control of many different dmbss
Single database server
Clients on one or more LANS share a single database locatedn a single computer system
Replicated database server
Each server stores a separate copy of the needed data. Clients interact with the db server on their own LAN
Partitioned database server
minimize need for db synchronization by partitioning db contents among multiple db servers
Federated database server
is commonly used taccess data stored in dbs with incompatible storage models or dbmss.
What is UML? What type of modeling is it used for?
uml is the accepted standard Omodeling language of the industry.
Use case model
A collection of models that can be used tcapture system requirements based on use cases with the object-oriented approach
The objective of an use case model
is tidentify and define all of the elementary business processes that the system must support.
Use cases
a diagram tshow the various user roles and how these roles use the system