原始sql：
将表中数据按照name分组，其他字段展示最新的数据，于是，先要排序后，再进行分组
1 select a.name,count(*),a.datetime from
2 (select * from TableName where 1=1 and datetime >= "2020-1-9 11:00:00"
3 and datetime <= "2020-1-9 20:00:00" ORDER BY id DESC LIMIT 100000) a
4
将sql拆解：
1 1.
2 select * from TableName where 1=1 and datetime >= "2020-1-9 11:00:00"
3 and datetime <= "2020-1-9 20:00:00" ORDER BY id DESC LIMIT 100000
4
5 2.
6 select a.name,count(*),a.datetime from
7 (1中sql) a
8
SQLAlchemy的写法：
1 sql_text = ' 1=1 and datetime >= "2020-1-9 11:00:00" and datetime <= "2020-1-9 20:00:00"'
2
3 #相当于 sql拆解中的1
4 resSub = db.session.query(TableName).filter(text(sql_text)).order_by(TableName.id.desc()).limit(10000).subquery()
5
6 #相当于 sql拆解中的2
7
