How can i remove the milliseconds from date time in rails?

I have to compare the date in rails to get the values after that date I have send the date as "2013-03-04T06:26:25Z"but actually the record in the db contains date as follows 2013-03-04 06:26:25.817149 so when i check with the date it also returns that record but i want records after that date. how can i remove the milliseconds from the db? please help me.