KM_Pres_PA_Ch2_update_fall_05

KM_Pres_PA_Ch2_update_fall_05 - Chapter 2 Project Q & A...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 2 Intro to Relational Model Diagramming Techniques Data Structure Diagrams (DSD) Entity Relationship Diagrams (ERD)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Relations Two dimensional table in which: Entries are single-valued Each column (field or attribute) has a distinct name All values in a column represent the same attribute Order of columns is immaterial Each row (record or tuple) is distinct Order of rows is immaterial Relations are NORMALIZED when they follow these rules
Background image of page 2
What is a normalized relation? 1. entries in table are single valued (normalized vs. non-normalized) Unnormalized example: ENROLLMENT(Schedule No., Room, Time, Student 1 , Student 2 , Student 3 ...Student 100 ) Normalized
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
(cont) 2. each column has a distinct name 3. all values in the column are instances of the same attribute Example in violation of this Period J98 F98 M98 A98 M98 J98 Jl98 Ag98. ..D98 30 Day 60 Day 90 Day 120 Day Over 120 Days What is wrong?? How do we fix it??
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 20

KM_Pres_PA_Ch2_update_fall_05 - Chapter 2 Project Q & A...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online