Oracle8i interMedia Text Reference
Release 2 (8.1.6)

Part Number A77063-01

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Query Operators, 9 of 26


MINUS (-)

Use the MINUS operator to search for documents that contain one query term and you want the presence of a second query term to cause the document to be ranked lower. The MINUS operator is useful for lowering the score of documents that contain unwanted noise terms.

Syntax

Syntax  Description 

term1-term2

term1 minus term2 

Returns documents that contain term1. Calculates score by subtracting occurrences of term2 from occurrences of term1

Examples

Suppose a query on the term cars always returned high scoring documents about Ford cars. You can lower the scoring of the Ford documents by using the expression:

'cars - Ford'

In essence, this expression returns documents that contain the term cars and possibly Ford; however, the score for a returned document is the number of occurrences of cars minus the number of occurrences of Ford. If a document does not contain any occurrences of the term Ford, no value is subtracted from the score.


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