字段1            字段2                  字段3 
            A                 1                      100   
            A                 2                      100   
            B                 3                      100   
            B                 4                      100   
            C                 5                      100  
字段1
种类合计数  3  
在dbgrideh中怎样实现以上的功能,就是汇某一个字段的汇总个数。