条件求和，好难啊！
A B
20110501100
20110501101
20110501102
20110501103
20110502104
20110502105
20110502106
20110502107
20110502108
20110503109
20110504110
20110504111
20110504112
20110508113
20110508114
20110508115
20110508116
20110520117
20110520118
20110520119
20110522120
各个日期都可能重复，我现在要计算 20110504至20110520所对应的B列的值。
[解决办法]
=SUMIF(A1:A21,">=20110504",B1:B21)-SUMIF(A1:A21,">20110520",B1:B21)
[解决办法]
