Question

i have data,

Stamp                dataField1 dataFiel2
2012-05-23 23:59:59  ....        ....
2012-05-23 23:50:00  ....        ....
2012-05-24 24:43:23  ....        ....
2012-05-24 24:12:10  ....        ....
2012-05-25 25:15:00  ....        ....
2012-05-26 25:53:59  ....        ....

and i want to select every day last row and result should look li

Stamp                dataField1 dataFiel2
2012-05-23 23:59:59  ....        ....
2012-05-24 24:43:23  ....        ....
2012-05-26 25:53:59  ....        ....

Answer 1

How about this?

SELECT MAX(Stamp) as Stamp, dataField1, dataField2
FROM tableName
GROUP BY DAYOFYEAR(Stamp)

I would say use DAYOFYEAR instead of DAY as everyone stated. For difference, see below link.

Demo

In this demo, DAY gives 3 rows which is INCORRECT as oppose to 4 rows using DAYOFYEAR.