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Chapter 7: Advanced SQL and MySQL - Fifth Edition of PHP and MySQL for Dynamic Web Sites Visual QuickPro Guide

Page 229 - Table 7.3

It says 


Operator - ~

Meaning - Lowers a ranking if present

Operator: <

Meaning: Decrease a word's importance

I don't understand the difference between lowering importance and lowering ranking. Doesn't decreasing the importance decrease the ranking? Can someone please explain to me the difference between the 2?



Edited by Marvin
Changed Title to make 'versus' more obvious
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Sorry for the confusion here. It's a subtle difference. Here's what the MySQL manual says:


These two operators are used to change a word's contribution to the relevance value that is assigned to a row. The > operator increases the contribution and the < operator decreases it.



A leading tilde acts as a negation operator, causing the word's contribution to the row's relevance to be negative. This is useful for marking noise words. A row containing such a word is rated lower than others, but is not excluded altogether, as it would be with the- operator.

I guess I'd phrase it as ~ being more impactful than <. 

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