03_RelationalModel.pdf - CITS1402 Relational Database...

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CITS1402 Relational Database Management Systems Video 03 — Relational Model I Gordon Royle Department of Mathematics & Statistics
A simple model Small and/or personal databases often use I Plain Files + Text Editor, or I Microsoft Excel. You may even read that “Excel is the world’s most popular database” which—by some measures—has at least a grain of truth.
An Excel database The 10 highest-rated movies on IMDB 1 (July 2020). This intuitive tabular format underlies the relational model. 1 Internet Movie Database
Relational Terminology The relational model is based on formal mathematical concepts , so uses mathematical terminology in a precise way, e.g. I Relation, instance, tuple, attribute, field. In practice, databases are somewhat loosely based on the formal model, so more informal terminology is used, e.g. I Table, row, column, header . However, it is important to recognise both the formal terms and the informal terms.
Tables / Relations A table represents a collection of objects ( “entitites” ) 2 .

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