group by grouping sets计算每个分组的占比

计算每个分组的数量

select parent_dict_code,count(*) from tb_data_dict group by rollup(parent_dict_code) ;

计算占比，注意要*1.0，否则仍为整型，全为0

select parent_dict_code,count(data_dict_id),(select count(data_dict_id) from tb_data_dict) as sum_all,count(data_dict_id)/(select count(data_dict_id) from tb_data_dict)*1.0 from tb_data_dict group by grouping sets(parent_dict_code) ;

 coalesce(parent_dict_code,'total')本来是用来返回第一个非null值的，但是可以用来加一行合计数据：

select coalesce(parent_dict_code,'total'),count(data_dict_id) as g from tb_data_dict group by grouping sets((parent_dict_code),())