I have [income]- (REVENUE) table of accounts, each account can have multiple instances for one month. how can I find the last occurrence of all the accounts in a month (and then summarize all of these latest occurrences)?
account revenue revenue_date
1 100 2010-01-01
1 200 2010-02-03
1 300 2010-02-04
1 1000 2010-06-04
2 100 2010-02-01
2 200 2010-03-03
2 1300 2010-07-04
2 11000 2010-08-04
3 2100 2010-01-01
3 2200 2011-02-03
3 300 2011-02-04
3 221000 2011-06-04
4 222 2010-02-01
4 2222 2012-03-03
account revenue revenue_date
1 100 2010-01-01
1 200 2010-02-03
1 300 2010-02-04
1 1000 2010-06-04
2 100 2010-02-01
2 200 2010-03-03
2 1300 2010-07-04
2 11000 2010-08-04
3 2100 2010-01-01
3 2200 2011-02-03
3 300 2011-02-04
3 221000 2011-06-04
4 222 2010-02-01
4 2222 2012-03-03