round(cast(hospital_area as numeric) / cast(all_area as numeric) * 100,6)結果乘100，取6位小數，結果展示
select *,round(cast(hospital_area as numeric) / cast(all_area as numeric) * 100,6) as hospital_ratio_new,
round(cast(food_area as numeric) / cast(all_area as numeric) * 100,2) as food_tatio_new from area_relation_scenes
cast函數，將某個字段轉成某種類型
例如：cast(hospital_area as numeric) 將hospital_area(原本是字符串的)轉成numeric類型