asp去掉有负数的重复数据

表字段 id username point
1 a 1
2 b 5
3 c 8
4 a 10
5 b 5
6 a -1
7 b 20
要显示结果
b 30
c 8
去掉有负数的用户a
我用户的错误语句是
rs0.open "select username, sum(point)as point from tab where username not in(select point<0 group by username) and point>0 group by username",conn,1,1

 

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select username, sum(point) as point
from tab
where username not in (select username from tab where point<0 )
and point > 0
group by username