how write calendar expression in pivot table....

[#1]

filed 1    field 2     calendar

userid	username	date
1	xxx	1/08/2015
2	yyy	1/09/2015
3	zzz	1/10/2015

i want disply as a pivot table.....date filed shoud be calendar it should be automatic genarated.....can u plese give m e the expression.