Question

我尝试在SQLAlchemy（ORM）中执行以下请求：

SELECT id，ref_prog FROM stepvand_1c_1t.equipment_day_hour WHERE id IN（SELECT id FROM stepvand_1c_1t.equipment WHERE equipment_type ='L'）

我做了：

subq = session.query(Equipment)
subq = subq.filter(Equipment.equipment_type == "L").subquery()

query = session.query(EquipmentDayHour)
query = query.filter(EquipmentDayHour.id.in_(subq))

但这不起作用......

Python告诉我子请求有太多列。

Answer 1

我认为您应该只更改示例代码的一行：

# error: includes all columns of Equipment
`subq = session.query(Equipment)`
# correct: include only ID column
`subq = session.query(Equipment.id)`

但是，我相信你可以在没有子查询的情况下做到这一点：

query = (session.query(EquipmentDayHour).
         # version-1: if you have a relationship between EquipmentDayHour and Equipment
         join(Equipment).
         # version-2: if you do not have such relationship
         #join(Equipment, EquipmentDayHour.id==Equipment.id).
         filter(Equipment.equipment_type == "L")
        )

在SQLAlchemy中进行子请求

1 个答案: