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Editorial Team
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Asked: 2026-05-26T18:30:34+00:00

SELECT date( `captureTime` ) dateDay, DATE_FORMAT( `captureTime` , ‘%H’ ) dateHour, DATE_FORMAT( `captureTime` ,

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SELECT date( `captureTime` ) dateDay, DATE_FORMAT( `captureTime` , '%H' ) dateHour, DATE_FORMAT( `captureTime` , '%i' ) dateQuarter, max( channel1_Data ) , max( channel2_Data ) , max( channel3_Data ) , min( channel1_Data ) , min( channel2_Data ) , min( channel3_Data )
FROM `sensordata`
WHERE `Sensor_sensorSerialNo` =1
AND `captureTime` >= '2011-10-16 22:15:11'
AND `captureTime` <= '2011-10-17 23:59:59'

I want to get all data from 2011-10-16 22:15:11 to 2011-10-17 23:59:59 after running the select query. And the ‘captureTime‘ column also need be divided into three columns(i.e. ‘dateDay‘, ‘dateHour‘ and ‘dateQuater‘). However, only get one row result after running the above query. I can’t see anything wrong there.

Can anyone point out the errors? Thanks in advance!

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1 Answer

  1. Editorial Team

    min, max functions are aggregate functions and are usually used with Group By clause. However If you are not using Group By clause then Min or Max value will be returned after performing calculation on complete table data. So, only one row should be returned, that would be minimum or maximum. If you want other columns to be selected, then those columns must be present in Group By clause.
    MySql allowed this query to execute, but other dbms such as SQLServer wont even allow this query to be executed.

    http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html

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