What is the query syntax of SQLAlchemy
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.
