MySQL每个月的“ rate”最小值和最大值

Question

I have a table with two fields - a field for "date" entered as day/month/year and a field "rate"

date | rate

24/01/05 | 1.9754
26/01/05 | 1.3723
...
and so on

So, I like to find minimum and maximum values of "rate" for each month of year(s). My query selects only one row

SELECT DISTINCT DATE_FORMAT(date, '%d-%m-%y') as Date, MIN(rate) as r, MAX(rate) as mr FROM rates

Answer 1

This will get the rate values for each month and year

SELECT
    YEAR(date) AS thisYear,
    MONTH(date) AS thisMonth,
    MIN(rate) AS minRate,
    MAX(rate) AS maxRate
FROM rates
GROUP BY thisYear ASC, thisMonth ASC

If you need to have the individual date(s) on which the min or max occurs you'll need some additional grouping in there, however the above should suffice for your original question.