mysql query for both distinct and sum

I have a mysql fields like this:

url_id     time_spent
-------    ----------
开发者_如何转开发120         14
120         97  
120         14
120         97 

I want to display only 14 and 97 based on url_id(DISTINCT).

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select * from table group by url_id,time_spent

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SELECT DISTINCT a.url_id, a.time_spent FROM table a