Shulou(Shulou.com)06/01 Report--

Database engine

Pymysql takes its place-recommendation

If 2, pip install pymysql

If 3, pip3 install pymysql

After the installation is complete, use pip3 freeze to check what version is installed and so on.

MySQLdb python3 does not support it, and TM has not been updated for a long time.

Sudo yum install python-devel mysql-devel

MySQL-python-1.2.5, this is the mysql interface of python2.7.6.

Https://pypi.python.org/pypi/MySQL-python/1.2.5

Import MySQLdb

Mysqlclient django1.9 recommendation, python3.3+ support

Sudo yum install python-devel mysql-devel

Pip install mysqlclient

MySQL Connector/Python

$python manage.py makemigrations polls stored as amigration.$ python manage.py sqlmigrate polls 0001 just returns their SQL$ python manage.py check # this checks for any problems in your project without making migrations or touching the database.$ python manage.py migrate apply those changes to the database. The primary key _ id is automatically generated

Python manage.py shell

Basic data access > from books.models import Publisher > p1 = Publisher (name='Apress', address='....) > p1.save () > publisher_list = Publisher.objects.all () > publisher_list []

``objects.create () ``does not require save if the object is created and stored in the database in one step

> p1 = Publisher.objects.create (name='Apress',... Address='2855 Telegraph Avenue',.

Add the string representation of the module

Add a method _ _ unicode__ () to the Publisher object.

From django.db import modelsclass Publisher (models.Model): name = models.CharField (max_length=30) def _ unicode__ (self): return self.name > from books.models import Publisher > publisher_list = Publisher.objects.all () > publisher_list [,]

Data filtering

Filter () returns the collection

You can pass multiple parameters to filter () to narrow the selection:

> > Publisher.objects.filter (country= "U.S.A.", state_province= "CA") []

There is a double underscore between name and contains. The contains part is translated into LIKE statements by Django:

> Publisher.objects.filter (name__contains= "press") [] Note that the default = operator of SQL matches exactly

SELECT id, name, address, city, state_province, country, websiteFROM books_publisherWHERE name LIKE'% press%'; other lookup types are: icontains (case-independent LIKE), startswith and endswith, and range (SQLBETWEEN query). Appendix C describes all the lookup types in detail.

Get a single object. ``get () ``returns a single object

> Publisher.objects.get (name= "Apress") if the result is multiple objects, an exception will be thrown, and an exception will be thrown if the query does not return a result:

DoesNotExist: Publisher matching query does not exist.Publisher.DoesNotExist in your application, you can catch and handle this exception, like this:

Try: P = Publisher.objects.get (name='Apress') except Publisher.DoesNotExist: print "Apress isn't in the database yet." else: print "Apress is in the database." Data sorting

Orderly return of query results

If you need to sort by multiple fields (the second field is used if the value of the first field is the same), the minus sign-

Indicates reverse sorting:

> > Publisher.objects.order_by ("- state_province", "address") [,]

Limit the data returned

Take out a fixed number of records, cut sentences, do not support negative index, but can be queried in reverse order

> Publisher.objects.order_by ('- name') [0:2]

Update multiple objects

Update a record

> Publisher.objects.filter (id=52) .update (name='Apress Publishing')

Update multiple records.

> Publisher.objects.all () .update (country='USA') # the country field 2 # of all Publisher indicates the number of entries affected: the save () method, which updates all columns in a row. In some cases, we only need to update a few columns in the row.

Delete an object Delete an object in the database simply by calling the object's delete () method:

> p = Publisher.objects.get (name= "O'Reilly") > > p.delete () > > Publisher.objects.all () [] > Publisher.objects.filter (country='USA'). Delete () # Delete part > Publisher.objects.all (). Delete () # Delete all data in a table to prevent accidental deletion. Django requires that all data in the table be displayed with all (). Otherwise, report an error.

> Publisher.objects.delete () # must add all () Traceback (most recent call last): File "", line 1, in AttributeError: 'Manager' object has no attribute' delete'

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