A simple tutorial using the SQLAlchemy library under the Python Flask framework _python

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

First Import class Library:

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  <span style= "FONT-SIZE:18PX;" >from flask Import Flask from 
  flask.ext.sqlalchemy import sqlalchemy</span>

Then, you need to load the database path

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  <span style= "FONT-SIZE:18PX;" >mysqlname= ' <span style= ' Color:rgb (230, 219, 116); font-family: ' Source Code Pro '; font-size:13pt; Background-color:rgb (39, 40, 34); >mysql://user:passwd@127.0.0.1/student?charset=utf8</span> ' </span> 

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  <span style= "FONT-SIZE:18PX;" >app = Flask (__name__) 
  app.config[' sqlalchemy_database_uri '] = mysqlname 
  db = SQLALCHEMY (APP) </span > 

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

Below we will link the flask with the concrete table,

This creates a model

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  <span style= "FONT-SIZE:18PX;" >class User (db. Model): "" 
   
    store the number of each type of alarm, in minutes for 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 occurrence Time "" " 
   
    __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;</span> 

The above code, let Falsk and specific table Hello together

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

Now start the specific database operation:

1, insert

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  <span style= "FONT-SIZE:18PX;" >    p = User (...) 
      Db.session.add (P) 
      db.session.commit () </span> 

Constructs a piece of data from the class user

2, find

To get data with a primary key:
Code Example:

User.query.get (1)

<user
 u ' admin ' >

Reverse-check with an exact parameter:
Code Example:

Peter
=

User.query.filter_by (username= ' Peter '). 
#注意: Exact query function query.filter_by (), is queried by passing parameters The other enhanced query functions are Query.filter (), which are queried by passing an expression.

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 ()

[<user
 u ' admin ',
 <user U ' guest ';

Logical non 1:
Code Example:

Peter
=

User.query.filter (user.username
 !=

' Peter '). (a)

print (peter.id)

Logical Non 2:
Code Example:

From

sqlalchemy import

not_

peter
=

User.query.filter (not_ (user.username== ' Peter ')). A (

peter.id) print

Logic and:
Code Example:

from SQLAlchemy import

and_

peter
=

User.query.filter (and_ user.username== ' Peter ',
 User.email.endswith (' @example. com ')). A (

peter.id) print

Logical OR:
Code Example:

from SQLAlchemy import

or_

peter
=

User.query.filter (or_ user.username
 !=

' Peter ',
 User.email.endswith (' @example. com ')). A (

peter.id) print

Filter_by: This inside can only put the specific conditions, can not put a complex calculation,

Filter: This one can put some complex calculations

. First: Take the number one data

. All: Remove all data

There's another way to do things like sort, count, and so on.

3. Use SQL statements

You can use SQL Native statements directly from the previously constructed DB

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  <span style= "FONT-SIZE:18PX;" >insert_table.db.engine.execute (' ..... ') </span> 

4, delete

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  <span style= "FONT-SIZE:18PX;" >me = User (...) </span> 

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  <span style= "FONT-SIZE:18PX;" >db.session.delete (Me) 
  db.session.commit () </span> 

5, update the data

Code example:
 
u
=

User.query.first ()

u.username
=

' guest ' 
#更新数据和变量赋值那么简单, However, it must be an object returned through a query.

Db.session.commit ()