A simple tutorial on using the SQLAlchemy library in Python's flask framework

The SQLAlchemy in flask is more thorough than the SQLAlchemy package and is simpler in some ways

First import the class library:

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  From flask import flask from   flask.ext.sqlalchemy import SQLAlchemy

Then, you need to load the database path

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  Mysqlname= 'Mysql://user:passwd@127.0.0.1/student?charset=utf8'

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  App = Flask (__name__)   app.config[' sqlalchemy_database_uri '] = mysqlname   db = SQLALCHEMY (APP)

With the first two steps, we've got flask and the database connected.

Now we're going to link the flask with the specific table,

This creates a model.

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  Class User (db. Model): ""        stores the number of each type of alarm, in minutes for the statistics     :p Aram source:string, Alarm source     :p Aram Network_logic_area:string, the alarm belongs to the logos Network area     :p Aram Start_time:datetime, alarm occurs "" "        __tablename__ = ' Hello '     id = db. Column (db. Integer, Primary_key = True)     Source = db. Column (db. String (255))     Network_logic_area = db. Column (db. String (255))     start_time = db. Column (db. DateTime)     count = db. Column (db. Integer)        def __init__ (self, source, Network_logic_area, Start_time, count):       Self.source = Source self       . Network_logic_area = Network_logic_area       self.start_time = start_time       Self.count = Count        def alter (self ):       Self.count + = 1;

The above code, let Falsk and specific table hello linked together

In this class, we first specify the table and then list the columns in the table, and finally define an initialization function that inserts the data later using the

Now start the specific database operation:

1. Insert

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      p = User (...)       Db.session.add (P)       db.session.commit ()

A data is constructed from the class user

2. Find

Get the data with the primary key:
Code Example:

User.query.get (1)
 
  

To counter-check with an exact parameter:
Code Example:

Peter=user.query.filter_by (Username= ' Peter '). First () #注意: Exact query function query.filter_by (), which is queried by passing parameters Other enhanced query functions are Query.filter (), which are queried by pass-through expressions. Print (peter.id) #如果数据不存在则返回None

Fuzzy query:
Code Example:

User.query.filter (User.email.endswith (' @example. com ')). All () [
 
  
   
  , 
  
   
    
   ]
  
   
 
  

Logic not 1:
Code Example:

Peter=user.query.filter (User.username! = ' Peter '). First () print (peter.id)

Logic not 2:
Code Example:

Fromsqlalchemy Importnot_peter=user.query.filter (Not_ (user.username== ' Peter ')). First () print (peter.id)

Logic with:
Code Example:

Fromsqlalchemy Importand_peter=user.query.filter (And_ (user.username== ' Peter ', User.email.endswith (' @example. com ') )). First () print (peter.id)

Logical OR:
Code Example:

Fromsqlalchemy Importor_peter=user.query.filter (or_ (user.username! = ' Peter ', User.email.endswith (' @example. com ')) ). First () print (peter.id)

Filter_by: This can only be put into a specific condition, can not put a complex calculation,

Filter: You can put some complicated calculations in this.

. First: Take the number one data

. All: Remove all data

There's another way to sort, count things like that

3. Using SQL statements

You can directly use SQL's native statements from the previously constructed DB

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  Insert_table.db.engine.execute (' ... ')

4. Delete

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  me = User (...)

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  Db.session.delete (Me)   db.session.commit ()

5. Update data

Code Example:u=user.query.first () u.username= ' guest ' #更新数据和变量赋值那么简单, but must be the object returned by the query. Db.session.commit ()

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