Flask framework operation database_ Add, delete, modify and query statements

1、 increase ：

Create entity class objects （ Rows of the database ）：
For example, to User In the table user_name and password add to ‘ Zhang San ’ and ‘123456’ The line of ：

#1. Create objects 
user1 = User(user_name=" Zhang San ",password="123456")

#2. Add session :
db.session.add(user1)

#3. Submit 
db.session.commit()

2、 check

There is one for each model class query object ,

#  For example, retrieve user modular （ surface ） All the lines in ：
User.query.all()

#  Search by condition , Use filters filter() To configure query object ：
user1 = User.query.filter(User.user_name==' Zhang San ').first()

3、 Change ：

#1、 Query and find the data that needs to be modified 
user1 = User.query.filter(User.user_name==' Zhang San ').first()

#2、 Modify the line ：
user1.user_name=' Zhang Xiaobao '

#3、 Commit transaction ：
db.session.commit()

4、 Delete

#1、 Take out the data to be deleted ：
user1 = User.query.filter(User.user_name==' Zhang San ').first()

#2、 Delete data ：
db.session.delete(user1)

#3、 Commit transaction ：
db.session.commit()