Using DATEADD in sqlalchemy

问题

How can I rewrite the following sql statement with sqlalchemy in python. I have been searching for 30 mins but still couldn't find any solutions.

DATEADD(NOW(), INTERVAL 1 DAY)

INSERT INTO dates (expire)
VALUES(DATEADD(NOW(), INTERVAL 1 DAY))

Thanks in advance

回答1:

SQLAlchemy dates automagically map to Python datetime objects, so you should just be able to do:

from sqlalchemy import Table, Column, MetaData, DateTime
from datetime import datetime, timedelta

metadata = MetaData()
example = Table('users', metadata,
   Column('expire', DateTime)
)

tomorrow = datetime.now() + timedelta(days=1)

ins = example.insert().values(expire=tomorrow)

回答2:

For completeness sake, here is how you'd generate that exact SQL with using sqlalchemy.sql.func:

from sqlalchemy.sql import func
from sqlalchemy.sql.expression import bindparam
from sqlalchemy import Interval

tomorrow = func.dateadd(func.now(), bindparam('tomorrow', timedelta(days=1), Interval()))

which results in:

>>> from sqlalchemy.sql import func
>>> func.dateadd(func.now(), bindparam('tomorrow', timedelta(days=1), Interval(native=True)))
<sqlalchemy.sql.expression.Function at 0x100f559d0; dateadd>
>>> str(func.dateadd(func.now(), bindparam('tomorrow', timedelta(days=1), Interval(native=True))))
'dateadd(now(), :tomorrow)'

Alternatively you could use a text() object to specify the interval instead:

from sqlalchemy.sql import func
from sqlalchemy.sql.expression import text

tomorrow = func.dateadd(func.now(), text('interval 1 day'))

回答3:

Doobeh beat me to it while I was typing, here's a flask-sqlalchemy example I was going to post though (to compliment the plain sqlalchemy example):

from flask.ext.sqlalchemy import SQLAlchemy
from datetime import datetime, timedelta

db = SQLAlchemy()

class Thing(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    created = db.Column(db.DateTime)

c = Thing(created = datetime.utcnow() + timedelta(days=1))
print repr(c.created)
# datetime.datetime(2013, 3, 23, 15, 5, 48, 136583)

You can pass default as a callable too:

from flask.ext.sqlalchemy import SQLAlchemy
from datetime import datetime, timedelta

db = SQLAlchemy()

def tomorrow():
    return datetime.utcnow() + timedelta(days=1)

class Thing(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    publish_date = db.Column(db.DateTime, default=tomorrow)

回答4:

You may use MySQL timestampadd insted dateadd.

More detail http://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_timestampadd

回答5:

from datetime import datetime, timedelta
from dateutil import tz

new_date = datetime.now(tz=tz.tzlocal()) + timedelta(days=1)
new_item = Expire(expire=new_date)
session.save(new_item)
session.commit()

来源：https://stackoverflow.com/questions/15572292/using-dateadd-in-sqlalchemy

标签

python

sql

sqlalchemy

Flask

flask-sqlalchemy