MySQL - Calculating a value from two columns in each row, using the result in a WHERE or HAVING clause

Posted by taber on Stack Overflow See other posts from Stack Overflow or by taber
Published on 2012-06-11T03:23:56Z Indexed on 2012/06/11 4:40 UTC
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I have a MySQL db schema like so:

id    flags     views    done
-------------------------------
1     2         20       0
2     66        100      0
3     25        40       0
4     30        60       0 

... thousands of rows ...

I want to update all of the rows whose flags / views are >= 0.2. First as a test I want to try to SELECT to see how many rows would actually get updated. I tried:

SELECT flags/views AS poncho FROM mytable HAVING poncho > 0.2

But this only returns like 2 rows and I know there should be a lot more than that. It seems like it's calculating the poncho value on all rows or something odd. What am I doing wrong?

Thanks!

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