Basierend auf den Informationen Ich bin geussing Sie eine Vereinigung (https://www.w3schools.com/sql/sql_union.asp) auf den verschiedenen Tabellen ausführen möchten.
In dem folgenden Beispiel werden die verschiedenen Tabellen erstellt, eine Vereinigung dieser verschiedenen Tabellen wird gemacht.
from sqlalchemy import Column, Integer, String, DateTime
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from datetime import datetime
Base = declarative_base()
class Human(Base):
__tablename__ = 'human'
id = Column('id', Integer, primary_key=True)
created = Column('created', DateTime)
name = Column('name', String(250))
def __init__(self, created, name):
self.created = created
self.name = name
def __repr__(self):
return '<{created} - {name}>'.format(created=self.created, name=self.name)
class Car(Base):
__tablename__ = 'car'
id = Column('id', Integer, primary_key=True)
created = Column('created', DateTime)
brand = Column(String(250))
def __init__(self, created, brand):
self.created = created
self.brand = brand
def __repr__(self):
return '<{created} - {brand}>'.format(created=self.created, brand=self.brand)
class Tree(Base):
__tablename__ = 'tree'
id = Column('id', Integer, primary_key=True)
created = Column('created', DateTime)
type = Column(String(250))
def __init__(self, created, type):
self.created = created
self.type = type
def __repr__(self):
return '<{created} - {type}>'.format(created=self.created, type=self.type)
engine = create_engine('sqlite:///')
session = sessionmaker()
session.configure(bind=engine)
ex_ses = session()
Base.metadata.create_all(engine)
human = Human(datetime.now(), 'Human a')
human2 = Human(datetime.now(), 'Human b')
car = Car(datetime.now(), 'Car a')
car2 = Car(datetime.now(), 'Car b')
tree = Tree(datetime.now(), 'Tree a')
tree2 = Tree(datetime.now(), 'Tree b')
ex_ses.add(human)
ex_ses.add(human2)
ex_ses.add(car)
ex_ses.add(car2)
ex_ses.add(tree)
ex_ses.add(tree2)
ex_ses.commit()
# Query
h = ex_ses.query(Human.created, 'name')
c = ex_ses.query(Car.created, 'brand')
t = ex_ses.query(Tree.created, 'type')
print(h.union_all(c).union_all(t).all())
Die letzte Abfrage (in der print-Anweisung) gibt:
[(datetime.datetime(2017, 7, 5, 5, 55, 54, 633863), 'Human a'),
(datetime.datetime(2017, 7, 5, 5, 55, 54, 633863), 'Human b'),
(datetime.datetime(2017, 7, 5, 5, 55, 54, 633863), 'Car a'),
(datetime.datetime(2017, 7, 5, 5, 55, 54, 633863), 'Car b'),
(datetime.datetime(2017, 7, 5, 5, 55, 54, 633863), 'Tree a'),
(datetime.datetime(2017, 7, 5, 5, 55, 54, 633863), 'Tree b')]
Diese Antwort basiert auf: How to union across multiple tables in SQLAlchemy?
Wie würden Sie die SQL schreiben? – univerio