introduction to database design with entity relationship diagrams
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Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 1
Yes! Database Design can be this fun
Mark Abramson, CEO, Forward Thought, Inc.10/9/2011
@mark__a
Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 2
THEORY & ELEMENTS
DEMO
Q&A
10/9/2011
Edgar F Codd
Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 3
• Microsoft BizSpark Startup Partner• Organizer of BizSparkSF
Meetup Group• Regular customer of all
tools used in demo• Schema-first kind of guy
10/9/2011
Disclosures
Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 4
What is a database design?
10/9/2011
Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 5
Why Database Design?
• Gives everyone a clear picture of your business rules and the data behind it
• Build consensus across business units• Separation of
concerns• Ensure data
accuracy• Fun
10/9/2011
Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 6
Entity / Relationship Model
• An Entity is some “thing” of interest• A Relationship defines the interaction
between one or more Entities
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Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 7
What’s the data look like?
10/9/2011
SalesOrderId OrderStatus OrderDate PlacedBy IsPriorityOrder CustomerId CurrencyId20001 Shipped 1/5/2011 Bob Smith 0 3 220002 Fulfillment 5/5/2011 John Doe 1 2 220003 Placed 5/7/2011 Brenda Lee 0 3 2
CustomerId CustomerName AccountNumber1 Woolworths 8383822 Rick's Café 2911013 Mill Valley Market 957588
Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 8
Entity
• Definition• Attributes• Data Types• NULL option• Primary Key• Foreign Key• Identity Columns
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Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 9
Relationship
• Definition• Identifying• Non-Identifying
10/9/2011
Non-Identifying Relationship
Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 10
Relationship (2)
• Recursive references• Associative / Many-To-Many /
“Join Tables”
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Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 11
Cardinality• How many instances of each entity may be
involved or must be involved?
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Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 12
Keys
• Primary Keys• Foreign Keys• Candidate Keys• Composite Keys
10/9/2011
Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 13
Normalization
10/9/2011
SalesOrderId OrderStatus OrderDate PlacedBy CustomerAccountNumber CreditLimit
20001 Shipped 1/5/2011 Bob Smith 838382 5000
20002 Fulfillment 5/5/2011 John Doe 291101 10000
20003 Placed 5/7/2011 Brenda Lee 957588 7500
Denormalization
Normalization
Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 14
Getting Fancy
• First, second, third-normal form• Generalization• Nonspecific relations• Three-way relationships• Constraints• Referential Integrity actions• Zachman’s Framework
10/9/2011
Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 15
Exercise! Legacy Baggage
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Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 16
Tools for Creating Your Model
• Paper + Pen / Whiteboard• Drawing Tools: PowerPoint, Visio• ER Tools: Open Source / Community Editions– CA ERWin; Toad; SSMS; MySQL Workbench
• ER Tools: Midrange– Sparx Systems EA $199; Toad $479
• ER Tools: High End– CA ERWin $4000; Embarcadero $2000
10/9/2011
Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 17
Demo time!
• SQL Server Management Studio (“free”)– http://www.microsoft.com/download/en/details.aspx?id=7593
• RedGate SQL Data Generator ($295)– http://www.red-gate.com/products/sql-development/sql-data-generator/
• RedGate SQL Prompt Pro ($295)
– http://www.red-gate.com/products/sql-development/sql-prompt/
10/9/2011
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© 2011 Mark Abramson / #svcc 18
Resources
10/9/2011
Designing Quality Databases With Idef1X Information ModelsThomas A., M.D. Bruce$3.91 on Amazon!
The Data Model Resource Book, Vol. 1: A Library of Universal Data Models for All EnterprisesLen Silverston$45(also check out Vol. 2 and Vol. 3)
Image CreditsSlide 1: flickr/besser.jetztSlide 2: IBMSlide 3: flickr/Pete ReedSlide 4: flickr/Artful MagpieSlide 14: Amazon.comSlide 15: flickr/Jon AshcroftAll ER diagrams: Mark Abramson
SQL in a Nutshell: A Desktop Quick ReferenceKevin Kline, Brand Hunt, Daniel Kline$18 on Amazon
http://www.databaseanswers.org/data_modelsRepository of simple examples of db modelsFree!
http://publib.boulder.ibm.com/infocenter/wchelp/v5r6/index.jsp?topic=/com.ibm.commerce.data.doc/refs/rdmindex.htmIBM WebSphere data modelAlso search for ER Diagrams for other large systems to see how someone else addressed a set of entities and relationships (MS Dynamics, SAP, etc.)
www.StackOverflow.com
Introduction to Database Design / ER Diagrams
© 2011 Mark Abramson / #svcc 1910/9/2011
SV Code CampPeter Kellner
Attendees
Mom + Dad
Loving WifeThomas Bruce
Edgar Codd
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