mysql - How to get last 3 data of last 3 week days from a table -


i have table consisting of stock market's daily data. consists of various number of rows each day.i have column named 'high' in table. need calculate max(high) last 3 week days. ex:- if today wednesday need calculate max of last week's friday , week's monday,tuesday. know can if know date manually using query this.

select max(high) table_name date>='date'

but don't want want automate program written in php. how can achieve in both either php or sql appreciable. table has 6 columns

date,time,open,high,low,close

say suppose if table this

date        time       open      high     low     close 2015-05-06  09:30:00   2012.50   2020.5   2016.5  2014.0 2015-05-06  09:31:00   2013.50   2021.5   2014.5  2016.0 2015-05-06  09:32:00   2014.50   2021.75  2017.5  2013.0 2015-05-07  09:30:00   2011.50   2019.5   2018.5  2014.0 2015-05-07  09:31:00   2014.50   2022.5   2016.5  2015.0 2015-05-07  09:32:00   2012.50   2026.5   2017.5  2016.0 2015-05-08  09:30:00   2010.50   2024.5   2015.5  2017.0 2015-05-08  09:31:00   2013.50   2026.5   2017.5  2018.0 2015-05-08  09:32:00   2014.50   2028.5   2015.5  2019.0 2015-05-08  09:33:00   2014.50   2022.5   2017.5  2012.0 2015-05-11  09:30:00   2017.50   2025.5   2018.5  2013.0 2015-05-11  09:31:00   2018.50   2027.5   2019.5  2016.0 2015-05-11  09:32:00   2019.50   2024.5   2011.5  2017.0 2015-05-11  09:33:00   2020.50   2026.5   2017.5  2014.0 2015-05-12  09:30:00   2018.50   2023.5   2018.5  2018.0 2015-05-12  09:31:00   2017.50   2024.5   2017.5  2014.0 2015-05-12  09:32:00   2018.50   2023.5   2018.5  2013.0 2015-05-12  09:33:00   2017.50   2024.5   2019.5  2014.0 2015-05-12  09:34:00   2016.50   2023.5   2016.5  2012.0 2015-05-12  09:35:00   2017.50   2025.5   2018.5  2011.0

and if today's date 2015-05-13(wednesday) need max(high) of last 3 week days i.e 2015-05-12,11,08 2028.5.

presumably, have data on "week days".

select max(high) table_name t join      (select date       table_name       group date       order date desc       limit 3      ) dates      on t.date = dates.date;

presumably, either want condition on stock or group by, based on sample query.

you can make more efficient adding where clause. typically, last 3 working days within last week, or so:

select max(high) table_name t join      (select date       table_name       date >= date_sub(curdate(), interval 7 day)       group date       order date desc       limit 3      ) dates      on t.date = dates.date;

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