SQLAlchemy-对象关系教程ORM-Relationship

query.filter(User.name == ‘ed‘)

query.filter(User.name != ‘ed‘)

query.filter(User.name.like(‘%ed%‘))

query.filter(User.name.ilike(‘%ed%‘))

query.filter(User.name.in_([‘ed‘, ‘wendy‘, ‘jack‘]))

# works with query objects too:
query.filter(User.name.in_(
session.query(User.name).filter(User.name.like(‘%ed%‘))
))

query.filter(~User.name.in_([‘ed‘, ‘wendy‘, ‘jack‘]))

query.filter(User.name == None)
query.filter(User.name.is_(None))

query.filter(User.name != None)
query.filter(User.name.isnot(None))

# use and_()
from sqlalchemy import and_
query.filter(and_(User.name == ‘ed‘, User.fullname == ‘Ed Jones‘))

# or send multiple expressions to .filter()
query.filter(User.name == ‘ed‘, User.fullname == ‘Ed Jones‘)

# or chain multiple filter().filter_by() calls
query.filter(User.name == ‘ed‘).filter(User.fullname == ‘Ed Jones‘)

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

match()使用一个特定于数据库的 MATCH或 CONTAINS函数;它的行为会有所不同后端和不可用等后端SQLite。
query.filter(User.name.match(‘wendy‘))

print(session.query(User.name).filter(User.fullname=="shi jun2"))
--------------------------------------------
SELECT users.name AS users_name 
FROM users 
WHERE users.fullname = %(fullname_1)s

query=session.query(User.name).first()
print(query)
(‘shi‘,)
query=session.query(User.name).all()
print(query)
[(‘shi‘,), (‘shi2‘,)]
query=session.query(User.name).one()
print(query)

sqlalchemy.orm.exc.MultipleResultsFound: Multiple rows were found for one()

query=session.query(User.name).filter(User.name=="shi").one()#这里查询出的结果只有1条，所以不会报错
print(query)
(‘shi‘,)
如果有一条记录就返回一条记录，如果没有记录就返回NONE
query=session.query(User.name).filter(User.name=="shi").one_or_none()
(‘shi‘,)
print(query)
query=session.query(User.name).filter(User.name=="sh3").one_or_none()
print(query)
None

query=session.query(User.name).filter(User.name=="shi").scalar()
print(query)
shi

# for user in session.query(User).filter(text("id<224")).order_by(text("id")).all():
#     print(user)

#通过params传递参数,使用:来分开参数

# for user in session.query(User).filter(text("id>:value and name=:name")).params(value=1,name="fred").order_by(User.id).one():
#     print(user)

for user in session.query(User).from_statement(text("select * from users where name=:name")).params(name="shi").all():
    print(user)

print(session.query(User).filter(User.name.like("shi%")).count())
    使用func.count()统计


from sqlalchemy import func
for row in session.query(func.count(User.name),User.name).group_by(User.name).all():
    print(row)
    －－－－－－－－－－－－
    (1, ‘shi‘)
(1, ‘shi2‘)

select count(*) from table
==session.query(func.count(‘*‘)).select_from(User).scalar()