SQL 按天统计，按月统计和统计天数

确定要统计的时间字段，例句中为start_time

1. 从表TABLE_NAME中以字段START_TIME为参照，按天统计

select START_TIME, DATE_FORMAT(START_TIME,'%Y-%m-%d') as day, count(*) as sum from TABLE_NAME group by day;

2. 从表TABLE_NAME中以字段START_TIME为参照，按月统计

select START_TIME, DATE_FORMAT(START_TIME,'%Y-%m') as month, count(*) as sum from TABLE_NAME group by month;

3. 统计表TABLE_NAME中以字段START_TIME为参照，共多少天数据，多少条数据

select to_days(now()) - to_days(min(START_TIME)) as days, count(*) from TABLE_NAME;