Basic Computer Notions Databases

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Relational examples (cont'd)

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

The join with the baby table results in 2 records.
PhName MHt M# DelivMWtBWt
Jones 177 392382 7512 57.4 3.6
Jones 177 392382 7706 58.2 3.4

From these we can calculate the average weight.

We have carried out 4 relational operations (Join, Project, Select and Join).

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

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