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ISA 245 Database Midterm Exam With 100% Correct And Verified Answers
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ISA 245 Database Midterm Exam With 100% Correct And Verified Answers
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ISA 245 Database Midterm Exam With100% Correct And Verified Answers
flat file system - Correct Answer-- any file not managed by a
database
- information is stored in perminant data files
problems with flat file systems - Correct Answer-- data
redundancy
- data isolation
- integrity problems
- constraint problems
- only one person can access it at a time
data redundancy - Correct Answer-multiple copies of the
same data
data redundancy and data inconsistency - Correct Answer--
data redundancy = many copies of same data
- data inconsistency = different copies of the data display
different information
database - Correct Answer-shared collection of related data
used to support the activities of a particular organization
advantages of a database over flat file system - Correct
Answer-- Logical, coherent, internally consistent
-Designed, built, and filled with data for a specific purpose
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,database data manipulation - Correct Answer-- Sort -
ORDER BY
- Match - WHERE
- Link - JOIN
- Aggregate - AGGREGATE FUNCTIONS + GROUP BY
- Skip fields - done by the program automatically
- Calculate - AGGREGATE FUNCTIONS
- Arrange - SELECT
database management system (DBMS) - Correct Answer-
collection of programs that enables users to create and
maintain databases and control all access to them
role of DBMS - Correct Answer-provide an environment
that is both convenient and efficient for users to retrieve and
store information
benefits of a database - Correct Answer-- self describing
nature
- insulation between program and data
- support for multiple views of data
- multiuser system
- control of data redundancy
- data sharing
- enforcement of integrity constraints
- restriction of unauthorized access
- data independence
- back up and recovery files
3 database models - Correct Answer-- relational data model
- hierarchical data model
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, - network data model
relational data model - Correct Answer-Represents data as
relations / tables
network data model - Correct Answer-Represents data as record
types
Hierarchial Data Model - Correct Answer-Data as hierarchical tree
structure
most common data model - Correct Answer-relational data model
data model - Correct Answer-a diagram that represents entities in
the database and their relationships
abstraction - Correct Answer-a simplified representation of
something more complex.
database degrees of data abstraction - Correct Answer-- external
model
- conceptual model
- internal model
- physical model
external model - Correct Answer-- Users view of database
- Can contain multiple different external views
- Closely related to the real world as perceived by the user
conceptual model - Correct Answer-- Flexible data structuring
capabilities
-Data stored in database
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