python SQLAlchemy中子查詢subquery的使用

基本配置：

https://www.cnblogs.com/whycai/p/11963443.html

 

原始sql：

將表中數據按照name分組，其他字段展示最新的數據，於是，先要排序后，再進行分組

select a.name,count(*),a.datetime from 
(select * from TableName where 1=1 and datetime >= "2020-1-9 11:00:00" 
and datetime <= "2020-1-9 20:00:00" ORDER BY id DESC LIMIT 100000) a 
GROUP BY a.name ;

將sql拆解：

1.
select * from TableName where 1=1 and datetime >= "2020-1-9 11:00:00" 
and datetime <= "2020-1-9 20:00:00" ORDER BY id DESC LIMIT 100000

2.
select a.name,count(*),a.datetime from 
(1中sql) a 
GROUP BY a.name ;

 

 

SQLAlchemy的寫法：

sql_text = ' 1=1 and datetime >= "2020-1-9 11:00:00" and datetime <= "2020-1-9 20:00:00"'

#相當於 sql拆解中的1
resSub = db.session.query(TableName).filter(text(sql_text)).order_by(TableName.id.desc()).limit(10000).subquery()

#相當於 sql拆解中的2
res = db.session.query(resSub.c.name, func.count(resSub.c.name), resSub.c.datetime).group_by(resSub.c.name).all()