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34 lines
1.6 KiB
34 lines
1.6 KiB
<H2>1.1. What is a database?</H2>
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<p>
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You can define a database as a collection of data on one topic. It is organised in a way allowing to easily browse the information, make changes or add new items.
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</p>
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<p>
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Look at this diagram for one of the above examples: a simple phone book.
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<br><img src="img/01_02_example.png">
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<br>A diagram of a phone number database<br><br>
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The above picture shows a set of two contacts each of which is presented on a separate card. It appears that such a card can constitute a single line in a table:
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</p>
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<p>
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<table border="1" cellspacing="0" cellpadding="2">
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<tr><td colspan="2"><b>Contacts</b></td></tr>
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<tr><td><b>Name</b></td><td><b>Tel No.</b></td></tr>
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<tr><td>Joan</td><td>699 23 43 12</td></tr>
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<tr><td>Adam</td><td>711 19 77 21</td></tr>
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</table>
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</p>
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<p>
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<b>Terms and definitions</b>: A single data which constitutes a part of a greater collection can be called a <b>line</b> or more professionally a <b>record</b>. The collection is narmally called a <b>table</b>. Moreover, the most natural name for the table is one describing the data it offers/stores which is <b>Contacts</b>. Furthermore, each line in the table consists of <b>columns</b> often also called <b>fields</b>. In the table <em>Contacts</em> there are two columns (fields): <em>Name</em> and <em>Tel No.</em>.
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</p>
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<p>
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For simple uses a single table can make up a <b>database</b>. Many people consider these two equivalent. As you will see, for real databases we usually need more than one table.
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</p>
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<p>
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To sum up, you have already got a simple database with one table <em>Contacts</em>.
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<!-- -- > msa_whitepaper.pdf -->
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</p> |