How can I cut off results in a full-text (boolean mode) search?

I'm using a boolean mode full-text search:

SELECT *, match(Tournament.Name) against ('query' in boolean mode) as score FROM `tournaments` AS `Tournament` WHERE 1 =1 ORDER BY `score` desc LIMIT 20

What I wanted to do was to change the where clause to contain something li开发者_运维百科ke score > 0.5, but this threw an error about score being an unknown column.

Is there a way around this? Or is my method flawed?

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EDIT: For example, say I search for "cheese", I get the following results:

• Cheese is great
• I love cheese
• Cheese ftw
• Cake is nice too
• Anyone for a cuppa?

The query has successfully sorted the matches to the top (they have good scores), but the others (with scores of 0) are left in the result set. I want to filter out these low scoring results.

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Rick James answered this over at the MySQL dev forums.

He wrote:

"score" is derived, so it cannot be in WHERE. Use HAVING instead of WHERE in this situation

SELECT ... AS score
FROM ...
WHERE ...
HAVING score > 0.5
ORDER BY score DESC

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I suggest you have a look at the basic mysql functions, to extract substrings from strings and convert them into a number. You can use them in you were clause and compare the result to 0.5