GEO 488556 Lecture 5

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GEO 488/556Lecture 5
Wit is the sudden marriage of ideas which before
their union were not perceived to have any
relation. Mark Twain

• Douglas Flewelling
• University at Buffalo/Geography

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Readings?

• Arlow Neustadt - Chapters 12
• Brooks The Surgical Team

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Database Management Systems (DBMS)

• Provide services to manage buckets of data
• Basic function is to safely store and retrieve
  data
• Read
• Write
• Delete
• Query (Retrieve)

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Early DBMS Models

• Hierarchical
• Network

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Relational Model

• Tables (Relations)
• Collections of data
• Rows (Tuples)
• Data pertaining to an individual
• Fields (Attributes)
• A particular fact about the individuals

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Relational DB Model
Relation/Table
Rel_Name
Tuples/Rows
Attributes/Columns
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Dr. Dougs Homebrew
Homebrew
Name
Style
Kegs
Bottle22
Bottle12
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The Select Operator
Homebrew
Name
Style
Kegs
Bottle22
Bottle12
Macintyre
Scotch Ale
2
6
0
Slogdobber
Brown Ale
0
12
0
Ice Storm
Porter
0
0
0
Mead
My Honeys Raspberry
0
2
0
Brown Ale
Zings Tailchaser
3
0
12
Mead
Millennium Ginger
0
24
0
Pilsner
Rocky Raccoon
0
0
6
British Ale
Candlemas
1
2
36
9
The Select Operator
Homebrew
Name
Style
Kegs
Bottle22
Bottle12
Macintyre
Scotch Ale
2
6
0
Brown Ale
Zings Tailchaser
3
0
12
British Ale
Candlemas
1
2
36
10
The Select Operator
KegBrew
Kegs
Name
Style
Kegs
Bottle22
Bottle12
Macintyre
Scotch Ale
2
6
0
Brown Ale
Zings Tailchaser
3
0
12
British Ale
Candlemas
1
2
36
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The Project Operator
KegBrew
Kegs
Name
Style
Kegs
Bottle22
Bottle12
Macintyre
Scotch Ale
2
6
0
Brown Ale
Zings Tailchaser
3
0
12
British Ale
Candlemas
1
2
36
12
The Project Operator
KegBrew2
Name
Kegs
Bottle22
Bottle12
Style
Macintyre
2
6
Scotch Ale
0
Zings Tailchaser
3
0
Brown Ale
12
Candlemas
1
2
British Ale
36
13
The Project Operator
KegBrew2
Name
Kegs
Macintyre
2
Zings Tailchaser
3
Candlemas
1
14
The Union Operator
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Union Operator II
KegBrew2
Name
Macintyre
Zings Tailchaser
Candlemas
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The Cartesian Product
KegBrew2
Name
Macintyre
Zings Tailchaser
Candlemas
BottleBrew
Name
Zings Tailchaser
Rocky Raccoon
Candlemas
17
Difference Operator
KegBrew2
Name
Macintyre
Zings Tailchaser
Candlemas
18
Intersect Operator
KegBrew2
Name
Macintyre
Zings Tailchaser
Candlemas
19
The Join Operator
Bottle12
12
6
36
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Flexible Design

• High Cohesion
• One abstraction, not one function
• Low Coupling
• Limit the worldliness of an objects knowledge
• Even Distribution of Behavior
• Self-reliance
• Avoid state-passing
• Strong Modularity
• Group like things