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Chapter 14
Database Management Systems:
Getting Data Together
Databases
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database programs store information so
that users can quickly locate, organize,
and display information
databases are found on all sizes and
types of computers
Basic database components
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field - a group of related characters
record - a group of related fields
file (table) - a group of related records
database - one or more related files
Characteristics of a good
database
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data integrity - data is valid
data independence - data can be used by other
applications
data security
– only authorized individuals can access and/or
change data
– data should be protected against loss or damage
data maintenance - procedures exist for adding,
deleting, and updating records
avoid data redundancy - data should not be
unnecessarily repeated
Typical database features
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creation of a database
– user must specify the name and type of each field
to define the basic record structure
entering data
– includes adding, deleting, and modifying records
browse data - examine contents of files
query the database - extract specific data
organize - sort data based on user needs
generate reports
– determine content
– design layout
Database Models
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hierarchical, network, relational, object-oriented
relational model
– most flexible and easily understood
– most common model for PC databases
– database file is envisioned as a two-dimensional
table
• rows correspond to records
• columns correspond to fields
– may include several files
• data in files is linked by a key field
• key field - the contents of this field uniquely
identify a record
Object-oriented DBMS
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developed to store many types of data
– graphics, video, audio, etc.
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examples include
– medical record databases
– Geographical Information Systems (GIS)
– educational instruction systems
Data Warehousing
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data warehouse - a collection of data
that has been captured from a
database, on a scheduled basis, over a
scheduled period of time
data mining - use of statistical and
artificial intelligence techniques to
discover patterns, relationships, and
trends in data