SQLAlchemy -orm

Use orm to create a table
Connect to the database
Create Base Base Class
Create classes, add attributes, and add data type constraints
Create session
Add create instance add data
Add data to the database
submit data

Adding, deleting, modifying and checking the Flask database

def add_data():
user = User (add attribute data)
session.add(user)
sesssion.commit()

def search_data():
data = session.query(Usre).filter(conditional judgment).all()
print(data)

def update_data():
data = session.query(Usre).filter(conditional judgment).all()
data.attribute name = xxx
session.commit()

def delete_data():
data = session.query(Usre).filter(conditional judgment).all()
session.rollback()
session.delete(data)

sqlalchemy common data types

		Integer: Plastic surgery.
		 Float: Floating point type.
		 Boolean: Pass True/False in.
		 DECIMAL: Fixed-point type.
		 enum: enumerated type.
		 Date: Pass datetime.date() in. 2020 10 28
		def add_data():
		 user = User (add attribute data)
		session.add(user)
		sesssion.commit()
		def search_data():
		 data = session.query(Usre).filter(conditional judgment).all()
		print(data)
		def update_data():
		 data = session.query(Usre).filter(conditional judgment).all()
		 data.attribute name = xxx
		session.commit()
		def delete_data():
		 data = session.query(Usre).filter(conditional judgment).all()
		session.rollback()
		session.delete(data)
		 DateTime: Pass datetime.datetime() in. 2020 10 28 21 36 21
		 Time: Pass datetime.time() in. 21 36 21
		 String: Character type. You need to specify the length when using it, which is different from the Text type.
		 Text: Text type.
		 LONGTEXT: Long text type.

Column commonly used parameters and aggregate functions

Common parameters
default: The default value. When you set default=xxx, if you do not pass this data, then the database will display your settings
Of this value
nullable: Whether it is nullable. nullable=False means it cannot be empty
primary_key: Whether it is the primary key.
unique: Is it unique? When you set this parameter, then the data in the unified column cannot be the same, and the same will report an error
autoincrement: Whether to increase automatically.
onupdate: The function to be executed when updating.
name: the field mapping of the attribute in the database

Aggregate function
func.count
func.max
func.min
func.avg
func.sum