尝试SUMIF函数.参见 http://www.techonthenet.com/excel/formulas/sumif.php有关更多详细信息.

Try the SUMIF function. See http://www.techonthenet.com/excel/formulas/sumif.php for more details.

更具体地说，单元格C1的公式应为:

More specifically, the formula for cell C1 should be:

=SUMIF(A:A,A1,B:B)

假设A和B列分别是项目和数量.

Assuming columns A and B are item and quantity respectively.