一、group by 查询分组后 各组的内部条数
说明:表:survey_consumer ,字段:profession
SELECT COUNT(*) num,profession FROM survey_consumer GROUP BY profession
二、group by 查询分组后 组的条数(组条数有多少条)
select count(distinct profession) from survey_consumer
说明:表:survey_consumer ,字段:profession
SELECT COUNT(*) num,profession FROM survey_consumer GROUP BY profession
select count(distinct profession) from survey_consumer