Basic Computer Notions Databases

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Relational examples

Example relational tables

Question #1: What is average weight of babies delivered by Jones to mothers with heights > 170 cm?

First we Join the Mother and Physician tables.
M# MHt MBirth Ph# PhName
123456 150 4605 123 Smith
392382 177 4912 220 Jones
238427 162 5204 123 Smith
649308 174 5409 123 Smith
732293 155 5810 220 Jones

Next we Project the columns that we're interested in.

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Last modified: Wed, 2007 Mar 21 17:29:21

Slide show generated from dbms.html by Weasel 2007 Mar 21