在sqlalchemy中使用DATEADD

Question

如何在python中用sqlalchemy重寫以下sql語句。我一直在尋找30分鐘，但仍找不到任何解決方案。

DATEADD(NOW(), INTERVAL 1 DAY) 

或

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

在此先感謝

Answer 1

SQLAlchemy的日期自動地映射到Python datetime對象，所以你應該能夠做到：

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) 

Answer 2

Doobeh打我當我打字的時候，這是一個我將要發佈的flask-sqlalchemy例子（恭維平原SQLAlchemy的例子）：

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) 

您可以通過默認的調用也：

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) 

Answer 3

爲了完整起見，這裏是你將怎樣生成精確的SQL使用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())) 

導致：

>>> 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)' 

或者，您也可以使用text()對象，而不是指定的時間間隔：

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

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

Answer 4

您可以使用MySQL timestampadd insted的dateadd。

更多細節http://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_timestampadd

Answer 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()