已知表：
id             time
1             2007-10-20 9:30:02
2             2008-11-20 9:30:02
3             2008-10-20 9:30:02
4             2009-2-20 9:30:02
.........
想得出下面的表,weekdays是time里的月份里所包含周末的天数，即当月周六和周日一共的天数
id          time                 weekdays
1        2007-10-20 9:30:02          8
2        2008-11-20 9:30:02          10
3        2008-10-20 9:30:02          8
4        2009-10-20 9:30:02          9
.........