I think you want the strftime() method of the eval command;
strftime(X,Y)
This function takes an epochtime value, X, as the first argument and renders it as a string using the format specified by Y. For a list and descriptions of format options, refer to the topic "Common time format variables". This example returns the hour and minute from the _time field:
... | eval n=strftime(_time, "%H:%M")
Use the following to determine which pieces of _time to use for the date;
http://docs.splunk.com/Documentation/Splunk/6.1.4/SearchReference/Commontimeformatvariables
It would appear %F would be what you need (i.e. | eval n=strftime(_time, "%F")
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