The basic framework of the query syntax Flask

The basic syntax:

Model class name .query [. Filters]. Actuators

Commonly used SQLAlchemy query filters

filter	Explanation
filter()	Add the filter to the original query, the query returns a new
filter_by()	Add the equivalent filter to the original query, the query returns a new
limit	The value specified defines the original query results returned
offset()	Offset from the original query results returned by the query returns a new
order_by()	Sort the original query results according to specified conditions, to return a new query
group_by()	The original query results are grouped according to specified criteria, returns a new query

Commonly used SQLAlchemy query executor

method	Explanation
all()	Return query results as a list of all
first()	Returns the first result of a query, if not found, return None
first_or_404()	Returns the first result of a query, if not found, returns 404
get()	Returns the row corresponding to the primary key, if not present, returns None
get_or_404()	Returns the row corresponding to the primary key, if not present, returns 404
count()	Returns the number of query results
paginate()	Returns a Paginate object that contains the results within the specified range

Case Code:

    # Queries all character data 
    Print (PeopleInfo.query.all ()) 

    # query how much personal property 
    Print (PeopleInfo.query.count ()) 

    # query first personal matter 
    Print (PeopleInfo.query.first ()) 

    # query id figure 4 is [3 ways] 
    Print (PeopleInfo.query.get (4 ))
     Print (PeopleInfo.query.filter (PeopleInfo.id == 4 ) .first ())
     Print (PeopleInfo.query.filter_by (ID = 4 ) .first ()) 

    # query data for all character names ending g of [start / include] 
    Print (PeopleInfo.query.filter (PeopleInfo.name.endswith ( ' g ' )). All ()) 

    # query the name is not All data is equal to wang [2 ways] 
    Print(PeopleInfo.query.filter (PeopleInfo.name! = ' Wang ' ) .all ()) 

    # query all the data [2 ways] name and email are beginning to li 
　　 Print (PeopleInfo.query.filter (PeopleInfo.name. startsWith ( ' Li ' )). filter (PeopleInfo.email.startswith ( ' Li ' )). All ())
     Print (PeopleInfo.query.filter (PeopleInfo.name.startswith ( ' Li ' ), PeopleInfo.email.startswith ( ' Li ' )). All ()) 

    # query password is `` email` 123456` or all of the data to the end of `itheima.com` 
    from SQLAlchemy Import or_
     Print(PeopleInfo.query.filter (or_ (PeopleInfo.password == ' 123456 ' , PeopleInfo.email.endswith ( ' itheima.com ' ))). All ()) 

    # query id [1, 3, 5, 7, 9] character list 
    Print (PeopleInfo.query.filter (PeopleInfo.id.in _ ([. 1,. 3,. 5,. 7, 9 ])). All ()) 

    # query name is character data liu 
    Print (PeopleInfo.query .filter_by (name = ' liu ' ) .all ()) 

    # queries all character data, and to sort mail 
    # descending 
    print (PeopleInfo.query.order_by (PeopleInfo.email.desc ()). All ())
     # ascending 
    print (PeopleInfo.query.order_by (PeopleInfo.email.asc ()). all ())

    # Page 3, page 2 of query data 
    # Page = None, the first few pages 
    # per_page = None Per few data 
    paginates = PeopleInfo.query.paginate (Page = 1, per_page = 2 )
     # the first few pages 
    print (paginates.page)
     # 　page a few 
    Print (paginates.per_page)
     # total number of data 
    Print (paginates.total)
     # data for the current page 
    Print (paginates.items)

Model Class Code:

from flask import Flask
from flask_sqlalchemy import SQLAlchemy


app = Flask(__name__)

# Set URL database connected 
the app.config [ ' SQLALCHEMY_DATABASE_URI ' ] = ' MySQL: // the root: [email protected]: 3306 / Test '

the app.config [ ' SQLALCHEMY_TRACK_MODIFICATIONS ' ] = True
 # will be displayed when the query of the original SQL statement 
the app.config [ ' SQLALCHEMY_ECHO ' ] = True
db = SQLAlchemy(app)

# Define the model 
class BookInfo (db.Model):
     # Set the table name 
    __tablename__ = ' BookInfo ' 
    # after the primary key, automatic growth since 
    the above mentioned id = db.Column (db.Integer, primary_key = True)
    name = db.Column(db.String(20),unique=True,nullable=False)
    pub_date = db.Column(db.Date,nullable=True)
    readcount = db.Column(db.Integer,default=1)
    commentcount = db.Column(db.Integer,default=1)
    is_delete = db.Column(db.Boolean,default=False)


    def __repr__(self):
        return self.name

class PeopleInfo(db.Model):
    __tablename__ = 'peopleinfo'
    id = db.Column(db.Integer,primary_key=True)
    name = db.Column(db.String(20),unique=True)
    password = db.Column(db.String(20),nullable=False)
    email = db.Column(db.String(50),nullable=True)
    #设置外键
    book_id = db.Column(db.Integer,db.ForeignKey('bookinfo.id'))

    def __repr__(self):
        return self.name

if __name__ == '__main__':
    app.run(debug=True)