Database Management Systems

Task of searching the database to a stored record for processing is called
data retrieval
The four interrelated components of the database concept are the DBMS, the DBA, the physical database and
users
A description of the physical arrangement of records in the database is the
internal view
A description of the logical/abstract, schema is the
conceptual view
Defines how a user sees the portion of the database he or she is authorized to access, subschema, is the
user view
May provide many distinct views of the database
user view
Users access the database by
direct query
Identifies, for the database management system, the names and relationships of all data elements, records, and files that comprise the data
DDL
Enables application programs to interact with and manipulate the database
DML
Written in fourth-generation language, allows users to retrieve and modify data, and reduces reliance on programmers
SQL
The way to access data is by following a predefined data path in what model
hierarchial
Data is represented on two-dimensional tables, users perceive they are manipulating a single table
relational database model
Occurs because of data redundancy
update anomaly
Most serious problem with unnormalized databases
deletion anomaly
Tables are provided by a link table for what type of connection
M:M
User view, schema, and internal view are levels of the database defined by the
DDL
Nouns that are depicted by rectangles on an entity relationship diagram are
entities
Preserved in a centralized database by using a lockout procedure
data currency
Free of transitive dependencies
third normal
A proprietary programming language a DBMS uses to retrieve, process, and store data
DML
Permits end users and professional programmers to access date in the database directly without the need for conventional programs
query language
The number of instances or records that pertain to a specific entity
occurence
Data elements that define an entity
attributes
The degree of association between two entities
cardinality
Physically connect logically related tables to achieve the association described in the data model
foreign keys
A new item cannot be added to the table until at least one entity uses a particular attribute item
insertion anomaly
If an attribute item used by only 1 entity is deleted, all the info about that attribute item is lost
deletion anomaly
A modification of an attribute must be made in each of the rows in which the attribute appears
update anomaly