在SQLAlchemy中使用OR

Question

我查看了文档,我似乎无法找到如何在SQLAlchemy中进行OR查询.我只是想做这个查询.

SELECT address FROM addressbook WHERE city='boston' AND (lastname='bulger' OR firstname='whitey')

应该是这样的

addr = session.query(AddressBook).filter(City == "boston").filter(????)

Answer 1

SQLAlchemy的重载位运算符&,|并~因此而不是与丑陋和难以阅读前缀语法or_()和and_()(像巴斯蒂安的答案),你可以使用这些运营商:

.filter((AddressBook.lastname == 'bulger') | (AddressBook.firstname == 'whitey'))

请注意,由于按位运算符的优先级,括号不是可选的.

所以你的整个查询看起来像这样:

addr = session.query(AddressBook) \
    .filter(AddressBook.city == "boston") \
    .filter((AddressBook.lastname == 'bulger') | (AddressBook.firstname == 'whitey'))

Answer 2

从教程:

from sqlalchemy import or_
filter(or_(User.name == 'ed', User.name == 'wendy'))

Answer 3

对于 SQLAlchemy ORM 2.0， 和|都or_被接受。

文档

from sqlalchemy.future import select
from sqlalchemy.sql import or_


query = select(User).where(or_(User.name == 'ed', User.name == 'wendy'))
print(query)

# also possible:

query = select(User).where((User.name == 'ed') | (User.name == 'wendy'))
print(query)

Answer 4

OR_运算符在OR查询组件数量未知的情况下非常有用.

例如,假设我们正在创建一个包含很少可选过滤器的REST服务,如果任何过滤器返回true,则应返回记录.另一方面,如果请求中未定义参数,则不应更改我们的查询.没有or_ function我们必须做这样的事情:

query = Book.query
if filter.title and filter.author:
    query = query.filter((Book.title.ilike(filter.title))|(Book.author.ilike(filter.author)))
else if filter.title:
    query = query.filter(Book.title.ilike(filter.title))
else if filter.author:
    query = query.filter(Book.author.ilike(filter.author))

使用or_函数可以将其重写为:

query = Book.query
not_null_filters = []
if filter.title:
    not_null_filters.append(Book.title.ilike(filter.title))
if filter.author:
    not_null_filters.append(Book.author.ilike(filter.author))

if len(not_null_filters) > 0:
    query = query.filter(or_(*not_null_filters))