How to do Aggregation using the class CL_SALV_AGGREGATION

The column of the ALV Display can be aggregated using the add_aggregation( ) method of the class CL_SALV_AGGREGATION. DATA lr_salv_aggregation TYPE REF TO cl_salv_aggregation. Lr_salv_aggregation = lr_salv_table=>get_aggregations( ). Lr_salv_aggregation->set_aggregation_before_items( abap_true ). Lr_salv_aggregation->add_aggregation( columnname = ‘AGE’                                                                 aggregation  =  if_salv_c_aggregation=>average ). The following aggregation types are available. If_salv_c_aggregation=>minimum. If_salv_c_aggregation=>maximum. If_salv_c_aggregation=>average. If_salv_c_aggregation=>total. If_salv_c_aggregation=>none.