final review
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Final Review. Sunday March 13th. Databases. Entities/Rows Attributes/Columns Keys Relationships Schema Instance. Databases. Entities/Rows -”theme” Attributes/Columns - characterisitics about entities Keys - unique row identifiers -EVERY ROW MUST HAVE ONE - PowerPoint PPT PresentationTRANSCRIPT
Final Review
Sunday March 13th
Databases
– Entities/Rows– Attributes/Columns– Keys– Relationships– Schema– Instance
Databases
– Entities/Rows -”theme”– Attributes/Columns - characterisitics about entities– Keys - unique row identifiers -EVERY ROW MUST
HAVE ONE– Relationships - associations among data -
• Foreign keys
– Schema - Table structure– Instance - Table contents
Good databases
• One copy of data - Why?
• Relationships between tables - How?
Databases operations
• Project
• Select
• Union
• Difference
• Product
Databases operations
• Project - pick columns
• Select - pick rows
• Union - combine two tables
• Difference - remove one table from another
• Product - create all possible pairs
Info Retrieval
• Use QUERIES to retrieve info from databases• Relationships
– One - to - one– One - to - many– Many - to - many
• Primary keys• Foreign keys
Info retrieval
• One - to - many:– The ONE is the primary key and is used as
a foreign key in the MANY’s table
• Many - to - many:– Cross reference table! To reduce into 1 -
to- many
Forms
• GUI• Front end of the database• Easier way to:
– Present info– Add content
• Adding an image to a form– Database stores a link to the image file (same as
html)
Reports
• Make DB look pretty!
• Easier way to:– Arrange data– Present data
• How is it done in access:– Wizard - easier– Design mode - customizable
Binary numbers
• What does each number position represent?
• Convert from hex to decimal
• Convert from binary to decimal
• Why represent info. Using binary numbers?
Representing info in binary
• Text• Color• Pictures• Sound• Anything!
– How are continuous signals represented in binary?
Representing info in binary
• Text• Color• Pictures• Sound• Anything!
– How are continuous signals represented in binary?
FIRST DISCRETIZE (OR DIGITIZE), THEN REPRESENT!
Privacy online
• Privacy Statements
• Cookies– Good?– Bad?– Can I do anything about it?
Privacy principles
• Limited collection– Knowledge and consent whenever appropriate
• Quality– Relevant to the purpose. Accurate and complete
• Purpose– Purpose should be stated. Limit use to purpose
• Use Limitation– Limit the use to the purpose unless authorized
Privacy Principles
• Security– Against disclosure, access, misuse, modification,
destruction, loss
• Openness– Let users know anything you can!
• Participation– Let users have control over their data (as much as
possible
• Accountability– The controller is accountable
First midterm stuff
• HTML
Second midterm stuff