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Chapter 11: Behind the Scenes: Databases and Information Systems
Life Without Databases
Database is a collection of related data that can be easily stored, sorted,
organized, and queried
A key attribute of databases is that information can be filtered so that you
can only see the info you really want (ex. Facebook)
Should I use databases for managing all types of data?
NO, simple lists can be created on word processing or spreadsheet software,
a spreadsheet in Microsoft excel, or table in Word
When is a list not appropriate?
If complex information needs to be organized or more than one needs access
to it, a list is not an efficient solution
What’s the problem with having two lists?
A great deal of duplicated data between the two lists
Data redundancy is when the same data exists in more than one place in a
database
Each time the information in the list changes, multiple lists must be updated
(data inconsistency)
Aside from data redundancy and inconsistency, are there any other problems
with using lists instead of databases?
With a list, anything can be entered in a row or column, even if that
information is incorrect
Information can be organized in many ways
How to handle incomplete data
Cant I Just exercise caution and set rules for updating lists?
Being careful does not avoid the most pressing problems or lists:
1. Inability of data to be shared
2. Data redundancy
How can I solve the problems associated with lists?
Single topics: lists is sufficient
Complex data: a database is sufficient
Database Building Blocks
Advantages to Databases
How do databases make out lives easier?
Allow easy retrieval and storage of large quantities of info
Extremely large electronic databases can provide info in seconds
THREE main ADVANTAGES:
1. Enable info storing
2. Promote data integrity
3. Flexible use of data
How do databases make information sharing possible?
One file is maintained, which reduces errors and increases efficiency
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How do databases promote data integrity?
Data integrity means that the data contained in the database is accurate and
reliable
Data centralization is having all your data in one central location. It helps
ensure data integrity by requiring data to be updated only by one place if the
data changes
How do databases provide flexibility?
You can reorganize the info they contain in a variety of ways to suit the needs
of the moment
Data flexibility makes info dissemination tasks easier
Disadvantages with databases
More complex to construct
Time-consuming, and expensive
Great care must be involved to ensure they will function properly
Database administrator (or database designer) is an individual trained in
the design and building of databases, to assist with the construction of large
databases
Data privacy
Database Terminology
How is data stored in a database?
THREE main COMPONENTS: fields, records, and tables
What is a field?
Displayed in columns
Each field is identified by a field name which is way of describing the field
What are data types?
A data type is assigned when fields are created in a database
There are 7 different common data types…..
1. Text field holds words
2. Numeric field holds numbers
3. Computational field (computed field) numeric field that stores
calculations
4. Data field holds data such as bdays and due dates
5. Memo field holds long pieces of text
6. Object field holds pictures, video clips, or documents
7. Hyperlink field stores hyperlinks to webpages
What is meant by a field size?
Is the max number of characters or numbers that a field can hold
If numeric field has a size of 5 it can hold a number as large as 99999
What are records and tables?
A record is a group of related fields
A table is a group of related records
Primary Keys
Can fields have the same values in the same table?
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YES, two students may have the same last name
A primary field or key field is one field that has a value unique to that
similar record
What makes a good primary key?
Numbers
Database Types
1. Relational
2. Object-oriented
3. Multidimensional
1) Relational Databases
What is a relational database?
Organizes data in table format by logically grouping similar data in relation
Tables are logically linked to each other by including their primary keys in
other tables with related info
Who invented the relational database?
E. F. Codd in 1970
2) Object-Oriented Databases
What is an object-oriented database?
Stores data in objects rather than in tables
Objects contain not only data, but also methods for processing or
manipulating that data
These databases store more types of data and able access to data faster
Why would I use an object-oriented database?
They are more adept at handling unstructured data. Ex, audio clips, video
clips, pictures, and extremely large documents
Binary Large Object (BLOB) is known as this data because it is actually
encoded in binary form
Are more complex
Need a query language to access and manage data, object query language
(OQL) is similar to structured query language
3) Multidimensional Databases
What is a multidimensional database?
Stores data in more than two dimensions
Organize data in cube format
Each data cube has a measure attribute which is the main type of data that
the cube is tracking
Feature attributes describe the measure attribute in some meaningful way
What are the advantages of multidimensional databases?
Can be easily customized to provide information to a variety of users
Can process data much faster than pure relational databases can
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