转自askmaclean论坛:
A4Nulls = (原始基数 - Nnulls)/ 原始基数
A4Nulls - Adjustment for NULLS
A4Nulls = (Orig_Card - NNulls)/Orig_Card
NNulls - Number of NULLS in a table column (dba_tab_columns.num_nulls)
转自askmaclean论坛:
A4Nulls = (原始基数 - Nnulls)/ 原始基数
A4Nulls - Adjustment for NULLS
A4Nulls = (Orig_Card - NNulls)/Orig_Card
NNulls - Number of NULLS in a table column (dba_tab_columns.num_nulls)