8.10. SQLAlchemy Core Update
>>> from sqlalchemy import update
8.10.1. SetUp
>>> from sqlalchemy import create_engine, MetaData, Table, Column
>>> from sqlalchemy import Integer, String, Date, Numeric, Enum
>>> from sqlalchemy import update
>>>
>>>
>>> engine = create_engine('sqlite:///:memory:', future=True)
>>> metadata = MetaData()
>>>
>>> astronaut = Table('astronaut', metadata,
... Column('id', Integer, primary_key=True),
... Column('firstname', String(50), nullable=False),
... Column('lastname', String(50), nullable=False),
... Column('agency', Enum('NASA', 'ESA', 'POLSA')),
... Column('birthdate', Date),
... Column('age', Integer),
... Column('height', Numeric(3,2)),
... Column('weight', Numeric(3,2)),
... )
>>>
>>> ASTRONAUTS = [
... {'firstname': 'Mark', 'lastname': 'Watney'},
... {'firstname': 'Melissa', 'lastname': 'Lewis'},
... {'firstname': 'Rick', 'lastname': 'Martinez'},
... ]
>>>
>>> with engine.begin() as db:
... metadata.create_all(db)
... result = db.execute(astronaut.insert(), ASTRONAUTS)
8.10.2. Update Statement
>>> query = (
... update(astronaut).
... values(firstname='Alex', lastname='Vogel').
... where(astronaut.c.id == 3)
... )
>>>
>>> with engine.begin() as db:
... result = db.execute(query)
8.10.3. Update Object
Like INSERT, it can also generate the SET clause based ont the given
parameters:
>>> query = (
... update(astronaut).
... where(astronaut.c.id == 3)
... )
>>>
>>> data = {'firstname': 'Alex', 'lastname': 'Vogel'}
>>>
>>> with engine.begin() as db:
... result = db.execute(query, data)
8.10.4. Update Expression
SQL Expression
>>> query = (
... update(astronaut).
... values(lastname=astronaut.c.firstname + '' + astronaut.c.lastname).
... where(astronaut.c.id == 3)
... )
>>>
>>> with engine.begin() as db:
... result = db.execute(query)
Note, that this example does not have any sense and it is used only to demonstrate the capability of the framework.