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| from sqlmodel import Field, Session, SQLModel, create_engine, select, union
class Team(SQLModel, table=True):
id: int | None = Field(default=None, primary_key=True)
name: str = Field(index=True)
headquarters: str
class Hero(SQLModel, table=True):
id: int | None = Field(default=None, primary_key=True)
name: str = Field(index=True)
secret_name: str
age: int | None = Field(default=None, index=True)
team_id: int | None = Field(default=None, foreign_key="team.id")
def test():
sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"
engine = create_engine(sqlite_url, echo=True)
SQLModel.metadata.drop_all(engine)
SQLModel.metadata.create_all(engine)
with Session(engine) as session:
team_preventers = Team(name="Preventers", headquarters="Sharp Tower")
team_z_force = Team(name="Z-Force", headquarters="Sister Margaret's Bar")
team_empty = Team(name="Empty", headquarters="Empty Team")
session.add(team_preventers)
session.add(team_z_force)
session.add(team_empty)
session.commit()
hero_deadpond = Hero(
name="Deadpond", secret_name="Dive Wilson", team_id=team_z_force.id,
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
team_id=team_preventers.id,
)
hero_spider_boy = Hero(name="Spider-Boy", secret_name="Pedro Parqueador")
session.add(hero_deadpond)
session.add(hero_rusty_man)
session.add(hero_spider_boy)
session.commit()
print("笛卡尔积+条件筛选")
print("#"*80)
with Session(engine) as session:
statement = select(Hero, Team).where(Hero.team_id == Team.id)
results = session.exec(statement)
for hero, team in results:
print("Hero:", hero, "Team:", team)
print("Inner Join")
print("#"*80)
with Session(engine) as session:
statement = select(Hero, Team).join(Team)
results = session.exec(statement)
for hero, team in results:
print("Hero:", hero, "Team:", team)
print("Left Outer Join")
print("#"*80)
with Session(engine) as session:
statement = select(Hero, Team).join(Team, isouter=True)
results = session.exec(statement)
for hero, team in results:
print("Hero:", hero, "Team:", team)
print("Right Outer Join")
print("#"*80)
with Session(engine) as session:
statement = select(Hero, Team).join(Hero, isouter=True)
results = session.exec(statement)
for hero, team in results:
print("Hero:", hero, "Team:", team)
print("Full Outer Join")
with Session(engine) as session:
statement = union(
select(Hero, Team).join(Team, isouter=True),
select(Hero, Team).join(Hero, isouter=True),
)
results = session.exec(statement)
for res in results:
print(res)
if __name__ == "__main__":
test()
|
