［整理］SQLAlchemy中query中filter和filter_by的区别

折腾：

［已解决］SQLAlchemy中filer_by中一次传入多个条件

期间，去查查，到底filter和filter_by，到底有何区别

Query API — SQLAlchemy 1.1 Documentation

Column Elements and Expressions — SQLAlchemy 1.1 Documentation

好像是：

在column的名字前加上：users_table.c

python – sqlalchemy filter multiple columns – Stack Overflow

－》又好像是：

应该写成类名加上column名？

sqlalchemy filter_by multiple parameters

python – How do I construct a slightly more complex filter using or_ or and_ in sqlalchemy – Stack Overflow

改为：

todayEventList = Event.query.filter_by(and_(Event.user_openid == curUser.openid, Event.start_date >= todayStart, Event.start_date <= todayEnd)).all()

结果：

File “/root/html/SIPEvents/sipevents/views.py”, line 396, in index

todayEventList = Event.query.filter_by(and_(Event.user_openid == curUser.openid, Event.start_date >= todayStart, Event.start_date <= todayEnd)).all()

TypeError: filter_by() takes exactly 1 argument (2 given)

估计是要把filter_by改为filter？

Query API — SQLAlchemy 1.1 Documentation

说是filter_by也支持多个参数啊。

SQL Expression Language Tutorial — SQLAlchemy 1.1 Documentation

sqlalchemy 教程 query

query.filter_by

使用SQLAlchemy – 廖雪峰的官方网站

<code>user = session.query(User).filter(User.id=='5').one()
</code>

SQLAlchemy入门 | 野猪林

<code>jack = session.query(User).filter_by(name='jack').one()
</code>

SQLAlchemy教程(一) – 小明明s à domicile

<code>statement = user_table.select(and_( user_table.c.created &gt;= date(2007,1,1), user_table.c.created &lt; date(2008,1,1))
result = statement.execute()  #检索
</code>

query filter_by sqlalchemy

->filter_by(), which uses keyword arguments

for name, in session.query(User.name).\

… filter_by(fullname=’Ed Jones’):

… print(name)

filter(), which uses more flexible SQL expression language constructs. These allow you to use regular Python operators with the class-level attributes on your mapped class:

for name, in session.query(User.name).\

… filter(User.fullname==’Ed Jones’):

… print(name)

python – What’s the difference between filter and filter_by in SQLAlchemy? – Stack Overflow

Object Relational Tutorial — SQLAlchemy 1.1 Documentation

->filter中，要用：类名.列名两个等号去判断

而filter_by中，只需要用：（不带类名的）列名单个等号就可以判断

－》filter中，语法更加贴近于，类似于，Python的语法。

－》此处好像是：

or_() 和 and_() 都只针对于 filter

［总结］

SQLAlchemy中的query，有filter和filter_by两个函数，其中：

filter －》 column == expression

传入参数的写法，要用：类名.列名两个等号去判断
举例：
query(User.name).filter(User.fullname==’Ed Jones’)
且更复杂的查询的语法，比如_and()，or_()等多个条件的查询，只支持filter
举例：
query.filter(or_(User.name == ‘ed’, User.name == ‘wendy’))
query.filter(and_(User.name == ‘ed’, User.fullname == ‘Ed Jones’))

filter_by －》keyword = expression

传入参数的写法，只需要用：（不带类名的）列名单个等号就可以判断。
－》filter中，语法更加贴近于，类似于，Python的语法。
举例：
query(User.name).filter_by(fullname=’Ed Jones’)

【后记】

Query API — SQLAlchemy 1.1 Documentation

filter(*criterion)

apply the given filtering criterion to a copy of this Query, using SQL expressions.

e.g.:

session.query(MyClass).filter(MyClass.name == ‘some name’)

Multiple criteria may be specified as comma separated; the effect is that they will be joined together using the and_() function:

session.query(MyClass).\

filter(MyClass.name == ‘some name’, MyClass.id > 5)

The criterion is any SQL expression object applicable to the WHERE clause of a select. String expressions are coerced into SQL expression constructs via the text() construct.

［整理］SQLAlchemy中query中filter和filter_by的区别

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