CIS 1000 Chapter 11: Chapter 11 CIS 1000

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CIS - Chapter 11 – Database and Information Systems
Databases – are collections of related data that can be easily stored, sorted, organized and queried
o Makes data more meaningful and useful
o Attempting to turn data into information
Problems with lists:
o Inability for data to be shared
o Data redundancy
 Any time complex info needs to be organized, or more than one person access it, a list is no longer efficient
– you need a database
Data Redundancy – amount of duplicated data between two lists
Data Inconsistency – if info is overlooked in one list that needs to be changed, it is not consistent with the
rest of the lists
o Hard to tell which entry is correct
 Data could also be added to a list in an inconsistent format – confusion
 Another problem is how to handle incomplete data – is it entered? Or just missing?
Advantages of Using Databases:
o Can store and retrieve large quantities of information easily
o Enable information sharing
Only one file is kept, increases efficiency, no need for multiple lists
o Promote data integrity – means that the data is accurate and reliable
Data centralization – helps ensure data integrity
o Allow the flexible use of data
Allows you to reorganize data in a variety of ways
Can manage and process larger amounts of data more efficiently
Disadvantages of Databases:
o Complex to construct and administer
o Time consuming and expensive to set up
o Need a database administrator or database designer
o Data privacy is an issue – lots of information in databases
Database Terminology:
o Three main components – fields, records and tables
Fields – a category of information in a database is stored in a field
o Are displayed in columns, has a field name
o Text fields, numeric fields, computed fields, date fields, memo fields, object fields, hyperlink
o Field size – defines the max number of characters a field can hold
Ex – size 5, can have number up to 99999
Record – a group of related fields
Table – a group of related records
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Primary Keys –the unique field – making a primary key and ensuring it is unique make it impossible to
duplicate records (ex – using a social insurance number, driver’s license #, plate #, order #)
DATABASE TYPES:
o Three major types – relational, object-oriented, multi-dimensional
Relational Database – organizes data in table format by logically grouping similar data into relations
o Tables are linked to each other by including their primary keys in other tables with related information
o Invented by E.F Codd in 1970
o Use structured query language – SQL
Object-Oriented Databases – stores data in objects, not in tables
o Contains not only data, but also methods for processing or manipulating that data
o Can store more types of data than relational, and access it faster
o Can handle unstructured data – nontraditional data such as audio, video, pictures, extremely large
documents – is all known as binary large object (BLOB)
o Are based on complex models
o Use object query language (OQL)
Multidimensional Databases – stores data in multiple dimensions (cube format) as opposed to relational
databases, which store data in two-dimensional tables
o Measure attribute – the main type of data that the cube is tracking
o Feature attributes – describe the measure attribute in some meaningful way
o Two main advantages – they can be easily customized and process data much faster
Ex – sites like eBay are set up using multi-dimensional = fast
DATABASE MANAGEMENT SYSTEMS: BASIC OPERATIONS
Database management system (DBMS) – is a specially designed application software (ex – Oracle or
Microsoft Access) that interacts with the user, other applications, and the database to capture and analyze
data – four main operations:
o Creating databases and entering data
o Viewing (or browsing) and sorting (indexing) data
o Extracting (querying) data
o Outputting data
Creating Databases and Entering Data:
o Data dictionary- a description of the data – defines the name, data type, length of each field
Called the field properties box in Access
o Set default values – the values the database will use for the field unless the user enters another value
o Metadata – integral part of the data dictionary – data describing other data
Input Forms – make it easy to transfer from other electronic sources
o Provides a view of the data fields to be filled, with appropriate labels to assist users in populating the
database
Data Validation – process of ensuring that data is correct and complete
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