I have no idea what this is called.

I need to GROUP by dates. However they are inputed by date and time in the same field. I need a way to cut off the last 6 digits before comparing the dates. Is there a way of doing this in MYSQL?

GROUP BY DATE(datetimefield)

Maybe I didn't explain clear enough. All my date fields are different.

ex. 20031213091555, 20031213094904

Same day, different times so regular GROUP will not work here. I need a way to cut off the last 6 digits then GROUP.

in that case;

GROUP BY left(datetimefield,length(datetimefield)-6)


<added>
A note for any future readers.

Be careful when choosing to store data in a field that is not ideal or you are doing some "independent thinking" on how numeric and date/time data is stored. Consider the "What ifs" for sorting, analysing and displaying the information in future times.

</added>