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CP102 Chapter Notes -Object Query Language, Query Language, Data Cube

Computer Science
Course Code
Mark Petrick

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CH11 Behind the Scenes: Databases and Information Systems
Database: collection of related data that can be easily stored, sorted, organized, and queried
o Most practical when there’s complex data that needs to be organized or shared
Problem with lists: data redundancy and inconsistency, how to handle incomplete data, organization can be labour intensive,
incorrect info can be entered
Database building blocks
Without them, you couldn’t store and retrieve large quantities of info easily
3 main advantages: enable information sharing, promote data integrity, allow flexible use of data
o provides data centralization, increases efficiency, reduces errors when data is entered/updated
o data integrity: data contained in database is accurate and reliable
o data centralization: ensures integrity
o makes information dissemination tasks easier
o can manage larger amounts of data and process that data more efficiently
disadvantages: time consuming, expensive to set up, privacy concerns
3 main components: fields, records, tables (or files)
field: database stores each category of information here
o data type (field type): when fields are created in the database, user assigns this. Common types include:
text field: can hold any combination of alphanumeric data but is most often used to hold words
numeric field stores numbers, values can be used to perform calculations
computational field: stores the contents of a calculation generated with a formula in the numeric field
date/time field: holds data such as birthdays and due dates
memo field: text field but can hold long pieces of text
object field: holds items such as pictures, video clips or documents
hyperlink field stores hyperlinks to web pages
o field size defines the maximum number of characters or numbers that a field can hold
record: group of related fields
table: group of related records
fields can have the same values in the same table
to keep records distinct, each record must have one field that has a value unique to that record
o unique field is called primary key or a key field. Makes it impossible to duplicate records
Database Types
relational database organizes data in table format by logically group similar data into a relation
o tables are logically linked to each other by including their primary keys in other tables with related information
o contain structured (analytical) data
object-oriented database stores data in objects rather than in tables
o store instructions for doing computations in the same places as they store data, they can usually process requests for info
faster than relationship databases can
o contain unstructured data- nontraditional data such as audio clips, video clips, pictures; known as binary large object
(BLOB) because it’s encoded in binary form
o much more complex data than relational databases
o use a query language to access and manage data
query language: specially designed computer language that is used to manipulate data in or extract data from a
many object-oriented databases use Object Query Language (OQL) which is similar to Structured Query Language
multidimensional database stores data in more than two dimension, ex eBay
o organizes information in cube format
o advantages: easily customized to provide info to a variety of users, process data much faster than relational databases
o each data cube has a measure attribute which is the main type of data that the cube is tracking
o other elements of the cube are known as feature attributes, which all describe the measure attribute in some meaningful
Database Management Systems: Basic Operations
database management system (DBMS) creates and manages databases
specially designed application software that interacts with other applications for 4 main operations: creating databases and entering
data; viewing and sorting data; querying (extracting) data; outputting data
Creating databases and entering data
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