sqlalchemy核心中的关联表

Question

我有3张桌子。 Cable ， PhysicalPoint和Interconnect 。

Cable包含两个PhysicalPoint （上坡，下坡），而Interconnect包含一个PhysicalPoint。 我想请求所有与Interconnect共同具有PhysicalPoint Cable 。 我用SQL而不是sqlalchemy来解决这个问题。

#cable, physicalpoint and interconnect are sqlalchemy.Table
c = cable.alias('c')
pdh = physicalpoint.alias('pdh')
puh = physicalpoint.alias('puh')
idh = interconnect.alias('idh')
iuh = interconnect.alias('iuh')

j = c.outerjoin(pdh, pdh.c.id==c.c.cab_downhill)\
    .outerjoin(puh, puh.c.id==c.c.cab_uphill)

# this is where I don't know what to do...
j2 = outerjoin(idh, pdh, pdh.c.id==idh.c.id)
j3 = outerjoin(iuh, puh, puh.c.id==iuh.c.id)

# this works but how to integrate the two other join ?
db.execute(select(c.c).select_from(j))

我希望这是足够全面的...预先感谢。

编辑：我写的SQL查询是这样的：

SELECT c.* 
FROM cable c
  LEFT JOIN physicalpoint pdh ON (pdh.id = c.cab_downhill)
  LEFT JOIN physicalpoint puh ON (puh.id = c.cab_uphill)
  LEFT JOIN interconnect idh ON (idh.id = pdh.id)
  LEFT JOIN interconnect iuh ON (iuh.id = puh.id)
WHERE idh.id='XXXX' OR iuh.id='XXXX'

Answer 1

您以与编写SQL查询完全相同的方式编写它：

j = c.outerjoin(pdh, pdh.c.id==c.c.cab_downhill)\
    .outerjoin(puh, puh.c.id==c.c.cab_uphill)\
    .outerjoin(idh, idh.c.id==pdh.c.id)\
    .outerjoin(iuh, iuh.c.id==puh.c.id)
session.execute(select([c]).select_from(j).where(or_(idh.c.id == "foo", iuh.c.id == "foo"))))