Shulou(Shulou.com)05/31 Report--

In this issue, the editor will bring you the query grammar about SQLAlchemy. The article is rich in content and analyzes and narrates it from a professional point of view. I hope you can get something after reading this article.

# simple query

Print (session.query (User). All ()

Print (session.query (User.name, User.fullname) .all ())

Print (session.query (User, User.name) .all ())

# query with conditions

Print (session.query (User). Filter_by (name='user1'). All ())

Print (session.query (User) .filter (User.name = = "user") .all ()

Print (session.query (User) .filter (User.name.like ("user%")) .all ()

# Multi-conditional query

Print (session.query (User) .filter (and_ (User.name.like ("user%"), User.fullname.like ("first%")) .all ())

Print (session.query (User) .filter (or_ (User.name.like ("user%"), User.password! = None) .all ())

# sql filtering

Print (session.query (User) .filter ("id >: id") .params (id=1) .all ()

# Association query

Print (session.query (User, Address) .filter (User.id = = Address.user_id) .all ()

Print (session.query (User) .join (User.addresses) .all ())

Print (session.query (User) .outerjoin (User.addresses) .all ())

# aggregate query

Print (session.query (User.name, func.count ('*'). Label ("user_count")) .group_by (User.name) .all ()

Print (session.query (User.name, func.sum (User.id) .label ("user_id_sum")) .group_by (User.name) .all ()

# subquery

Stmt = session.query (Address.user_id, func.count ('*'). Label ("address_count"). Group_by (Address.user_id). Subquery ()

Print (session.query (User, stmt.c.address_count) .outerjoin ((stmt, User.id = = stmt.c.user_id)) .order_by (User.id) .all ()

# exists

Print (session.query (User) .filter (exists () .where (Address.user_id = = User.id)

Print (session.query (User) .filter (User.addresses.any ()

The following is the mapping class:

Class User (Base):

_ _ tablename__ = "users"

Id = Column ("id", Integer, primary_key=True)

Name = Column ("name", String)

Fullname = Column ("fullname", String)

Password = Column ("password", String)

Addresses = relation ("Address", order_by= "Address.id", backref= "user")

Def _ _ init__ (self, id=None, name=None, fullname=None, password=None, addresses= []):

Self.id = id

Self.name = name

Self.fullname = fullname

Self.password = password

Self.addresses = addresses

Def _ repr__ (self):

Return "" .format (name=self.name, fullname=self.fullname, password=self.password, addresses=self.addresses)

Class Address (Base):

_ _ tablename__ = "address"

Id = Column (Integer, primary_key=True)

Email_address = Column (String, nullable=False)

User_id = Column (Integer, ForeignKey ("users.id"))

# user = relation ("User", backref= "addresses", order_by= "Address.id")

Def _ _ init__ (self, email_address=None):

Self.email_address = email_address

Def _ repr__ (self):

Return "" .format (email_address=self.email_address, user=self.user.name)

These are the syntax of the SQLAlchemy query shared by the editor. If you happen to have similar doubts, you might as well refer to the above analysis to understand. If you want to know more about it, you are welcome to follow the industry information channel.

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