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Database design, and information storage and retrieval

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ICT for Library <strong>and</strong> Information Professionals: A Training Package for Developing Countries<br />

? val(v26)=1976<br />

will retrieve the records published in 1976.<br />

This method of searching can be used to find whether data are available or not in a<br />

given field. For this functions a or p may be used.<br />

Search expression:<br />

? a(v12)<br />

This will retrieve records, which do not have data in field 12.<br />

Search expression:<br />

? p(v12)<br />

This will retrieve records, which have data in field 12.<br />

These can be combined like other search terms.<br />

Search expression:<br />

? p(v12) * a(v70)<br />

Module 4: <strong>Database</strong> Design, <strong>and</strong> Information Storage <strong>and</strong> Retrieval: Annex 02<br />

Page XI of XVII

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