How do I connect to a MySQL database using a python program?
转载于:https://stackoverflow.com/questions/372885/how-do-i-connect-to-a-mysql-database-in-python
Here's one way to do it:
#!/usr/bin/python
import MySQLdb
# Connect
db = MySQLdb.connect(host="localhost",
user="appuser",
passwd="",
db="onco")
cursor = db.cursor()
# Execute SQL select statement
cursor.execute("SELECT * FROM location")
# Commit your changes if writing
# In this case, we are only reading data
# db.commit()
# Get the number of rows in the resultset
numrows = cursor.rowcount
# Get and display one row at a time
for x in range(0, numrows):
row = cursor.fetchone()
print row[0], "-->", row[1]
# Close the connection
db.close()
Try using MySQLdb
There is a how to page here: http://www.kitebird.com/articles/pydbapi.html
From the page:
# server_version.py - retrieve and display database server version
import MySQLdb
conn = MySQLdb.connect (host = "localhost",
user = "testuser",
passwd = "testpass",
db = "test")
cursor = conn.cursor ()
cursor.execute ("SELECT VERSION()")
row = cursor.fetchone ()
print "server version:", row[0]
cursor.close ()
conn.close ()
MySQLdb is the straightforward way. You get to execute SQL queries over a connection. Period.
My preferred way, which is also pythonic, is to use the mighty SQLAlchemy instead. Here is a query related tutorial, and here is a tutorial on ORM capabilities of SQLALchemy.
1 - Setting
You must install a MySQL driver before doing anything. Unlike PHP, Only the SQLite driver is installed by default with Python. The most used package to do so is MySQLdb but it's hard to install it using easy_install.
For Windows user, you can get an exe of MySQLdb.
For Linux, this is a casual package (python-mysqldb). (You can use sudo apt-get install python-mysqldb
(for debian based distros), yum install MySQL-python
(for rpm-based), or dnf install python-mysql
(for modern fedora distro) in command line to download.)
For Mac, you can install MySQLdb using Macport.
2 - Usage
After installing, Reboot. This is not mandatory, But it will prevent me from answering 3 or 4 other questions in this post if something goes wrong. So please reboot.
Then it is just like using any other package :
#!/usr/bin/python
import MySQLdb
db = MySQLdb.connect(host="localhost", # your host, usually localhost
user="john", # your username
passwd="megajonhy", # your password
db="jonhydb") # name of the data base
# you must create a Cursor object. It will let
# you execute all the queries you need
cur = db.cursor()
# Use all the SQL you like
cur.execute("SELECT * FROM YOUR_TABLE_NAME")
# print all the first cell of all the rows
for row in cur.fetchall():
print row[0]
db.close()
Of course, there are thousand of possibilities and options; this is a very basic example. You will have to look at the documentation. A good starting point.
3 - More advanced usage
Once you know how it works, You may want to use an ORM to avoid writing SQL manually and manipulate your tables as they were Python objects. The most famous ORM in the Python community is SQLAlchemy.
I strongly advise you to use it: your life is going to be much easier.
I recently discovered another jewel in the Python world: peewee. It's a very lite ORM, really easy and fast to setup then use. It makes my day for small projects or stand alone apps, Where using big tools like SQLAlchemy or Django is overkill :
import peewee
from peewee import *
db = MySQLDatabase('jonhydb', user='john', passwd='megajonhy')
class Book(peewee.Model):
author = peewee.CharField()
title = peewee.TextField()
class Meta:
database = db
Book.create_table()
book = Book(author="me", title='Peewee is cool')
book.save()
for book in Book.filter(author="me"):
print book.title
This example works out of the box. Nothing other than having peewee (pip install peewee
) is required.
As a db driver, there is also oursql. Some of the reasons listed on that link, which say why oursql is better:
- oursql has real parameterization, sending the SQL and data to MySQL completely separately.
- oursql allows text or binary data to be streamed into the database and streamed out of the database, instead of requiring everything to be buffered in the client.
- oursql can both insert rows lazily and fetch rows lazily.
- oursql has unicode support on by default.
- oursql supports python 2.4 through 2.7 without any deprecation warnings on 2.6+ (see PEP 218) and without completely failing on 2.7 (see PEP 328).
- oursql runs natively on python 3.x.
Very similar to mysqldb:
import oursql
db_connection = oursql.connect(host='127.0.0.1',user='foo',passwd='foobar',db='db_name')
cur=db_connection.cursor()
cur.execute("SELECT * FROM `tbl_name`")
for row in cur.fetchall():
print row[0]
The tutorial in the documentation is pretty decent.
And of course for ORM SQLAlchemy is a good choice, as already mentioned in the other answers.
Oracle (MySQL) now supports a pure Python connector. That means no binaries to install: it's just a Python library. It's called "Connector/Python".
For python 3.3
CyMySQL https://github.com/nakagami/CyMySQL
I have pip installed on my windows 7, just pip install cymysql
(you don't need cython) quick and painless
If you do not need MySQLdb, but would accept any library, I would very, very much recommend MySQL Connector/Python from MySQL: http://dev.mysql.com/downloads/connector/python/.
It is one package (around 110k), pure Python, so it is system independent, and dead simple to install. You just download, double-click, confirm license agreement and go. There is no need for Xcode, MacPorts, compiling, restarting …
Then you connect like:
import mysql.connector
cnx = mysql.connector.connect(user='scott', password='tiger',
host='127.0.0.1',
database='employees')
try:
cursor = cnx.cursor()
cursor.execute("""
select 3 from your_table
""")
result = cursor.fetchall()
print result
finally:
cnx.close()
Also take a look at Storm. It is a simple SQL mapping tool which allows you to easily edit and create SQL entries without writing the queries.
Here is a simple example:
from storm.locals import *
# User will be the mapped object; you have to create the table before mapping it
class User(object):
__storm_table__ = "user" # table name
ID = Int(primary=True) #field ID
name= Unicode() # field name
database = create_database("mysql://root:password@localhost:3306/databaseName")
store = Store(database)
user = User()
user.name = u"Mark"
print str(user.ID) # None
store.add(user)
store.flush() # ID is AUTO_INCREMENT
print str(user.ID) # 1 (ID)
store.commit() # commit all changes to the database
To find and object use:
michael = store.find(User, User.name == u"Michael").one()
print str(user.ID) # 10
Find with primary key:
print store.get(User, 1).name #Mark
For further information see the tutorial.
Just a modification in above answer. Simply run this command to install mysql for python
sudo yum install MySQL-python
sudo apt-get install MySQL-python
remember! It is case sensitive.
Stop Using MySQLDb if you want to avoid installing mysql headers just to access mysql from python.
Use pymysql. It does all of what MySQLDb does, but it was implemented purely in Python with NO External Dependencies. This makes the installation process on all operating systems consistent and easy. pymysql
is a drop in replacement for MySQLDb and IMHO there is no reason to ever use MySQLDb for anything... EVER! - PTSD from installing MySQLDb on Mac OSX and *Nix systems
, but that's just me.
Installation
pip install pymysql
That's it... you are ready to play.
Example usage from pymysql Github repo
import pymysql.cursors
import pymysql
# Connect to the database
connection = pymysql.connect(host='localhost',
user='user',
password='passwd',
db='db',
charset='utf8mb4',
cursorclass=pymysql.cursors.DictCursor)
try:
with connection.cursor() as cursor:
# Create a new record
sql = "INSERT INTO `users` (`email`, `password`) VALUES (%s, %s)"
cursor.execute(sql, ('webmaster@python.org', 'very-secret'))
# connection is not autocommit by default. So you must commit to save
# your changes.
connection.commit()
with connection.cursor() as cursor:
# Read a single record
sql = "SELECT `id`, `password` FROM `users` WHERE `email`=%s"
cursor.execute(sql, ('webmaster@python.org',))
result = cursor.fetchone()
print(result)
finally:
connection.close()
ALSO - Replace MySQLdb in existing code quickly and transparently
If you have existing code that uses MySQLdb, you can easily replace it with pymysql using this simple process:
# import MySQLdb << Remove this line and replace with:
import pymysql
pymysql.install_as_MySQLdb()
All subsequent references to MySQLdb will use pymysql transparently.
Despite all answers above, in case you do not want to connect to a specific database upfront, for example, if you want to create the database still (!), you can use connection.select_db(database)
, as demonstrated in the following.
import pymysql.cursors
connection = pymysql.connect(host='localhost',
user='mahdi',
password='mahdi',
charset='utf8mb4',
cursorclass=pymysql.cursors.DictCursor)
cursor = connection.cursor()
cursor.execute("CREATE DATABASE IF NOT EXISTS "+database)
connection.select_db(database)
sql_create = "CREATE TABLE IF NOT EXISTS "+tablename+(timestamp DATETIME NOT NULL PRIMARY KEY)"
cursor.execute(sql_create)
connection.commit()
cursor.close()
first install the driver
pip install MySQL-python
Then a basic code goes like this:
#!/usr/bin/python
import MySQLdb
try:
db = MySQLdb.connect(host="localhost", # db server, can be a remote one
db="mydb" # database
user="mydb", # username
passwd="mydb123", # password for this username
)
# Create a Cursor object
cur = db.cursor()
# Create a query string. It can contain variables
query_string = "SELECT * FROM MY_TABLE"
# Execute the query
cur.execute(query_string)
# Get all the rows present the database
for each_row in cur.fetchall():
print each_row
# Close the connection
db.close()
except Exception, e:
print 'Error ', e
mysqlclient is the best as others only provide support to specific versions of python
pip install mysqlclient
example code
import mysql.connector
import _mysql
db=_mysql.connect("127.0.0.1","root","umer","sys")
#db=_mysql.connect(host,user,password,db)
# Example of how to insert new values:
db.query("""INSERT INTO table1 VALUES ('01', 'myname')""")
db.store_result()
db.query("SELECT * FROM new1.table1 ;")
#new1 is scheme table1 is table mysql
res= db.store_result()
for i in range(res.num_rows()):
print(result.fetch_row())
SQLAlchemy is the Python SQL toolkit and Object Relational Mapper that gives application developers the full power and flexibility of SQL. SQLAlchemy provides a full suite of well known enterprise-level persistence patterns, designed for efficient and high-performing database access, adapted into a simple and Pythonic domain language.
pip install sqlalchemy
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, scoped_session
engine = create_engine("mysql://<user_name>:<password>@<host_name>/<db_name>")
session_obj = sessionmaker(bind=engine)
session = scoped_session(session_obj)
# insert into database
session.execute("insert into person values(2, 'random_name')")
session.flush()
session.commit()
from sqlalchemy import Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, scoped_session
Base = declarative_base()
engine = create_engine("mysql://<user_name>:<password>@<host_name>/<db_name>")
session_obj = sessionmaker(bind=engine)
session = scoped_session(session_obj)
# Bind the engine to the metadata of the Base class so that the
# declaratives can be accessed through a DBSession instance
Base.metadata.bind = engine
class Person(Base):
__tablename__ = 'person'
# Here we define columns for the table person
# Notice that each column is also a normal Python instance attribute.
id = Column(Integer, primary_key=True)
name = Column(String(250), nullable=False)
# insert into database
person_obj = Person(id=12, name="name")
session.add(person_obj)
session.flush()
session.commit()
First, install python-mysql connector from https://dev.mysql.com/downloads/connector/python/
on Python console enter:
pip install mysql-connector-python-rf
import mysql.connector
To write database applications in Python, there are five steps to follow:
Import the SQL interface with the following command:
>>> import MySQLdb
Establish a connection with the database with the following command:
conn=MySQLdb.connect(host='localhost',user='root',passwd='') …where host is the name of your host machine, followed by the user name and password. In case of the root, there is no need to provide a password.
Create a cursor for the connection with the following command:
>>>cursor = conn.cursor()
Execute any SQL query using this cursor as shown below—here the outputs in terms of show a number of rows affected by this query:
cursor.execute('Create database Library') // Indicates how many rows affected
>>> cursor.execute('use Library')
>>>table='create table books(book_accno char(30) primary key, book_name
char(50),no_of_copies int(5),price int(5))'
>>> cursor.execute(table)
Finally, fetch the result set and iterate over this result set. In this step, the user can fetch the result sets as shown below:
>>> cursor.execute('select * from books')
>>> cursor.fetchall()
(('Py9098', 'Programming With Python', 100L, 50L), ('Py9099', 'Programming With Python', 100L, 50L))
you can connect your python code to mysql in this way.
import MySQLdb
db = MySQLdb.connect(host="localhost",
user="appuser",
passwd="",
db="onco")
cursor = db.cursor()
First install the driver (Ubuntu)
sudo apt-get install python-pip
sudo pip install -U pip
sudo apt-get install python-dev libmysqlclient-dev
sudo apt-get install MySQL-python
MySQL database connection codes
import MySQLdb
conn = MySQLdb.connect (host = "localhost",user = "root",passwd = "pass",db = "dbname")
cursor = conn.cursor ()
cursor.execute ("SELECT VERSION()")
row = cursor.fetchone ()
print "server version:", row[0]
cursor.close ()
conn.close ()
Best way to connect to MySQL from python is to Use MySQL Connector/Python because it is official Oracle driver for MySQL for working with Python and it works with both Python 3 and Python 2.
follow the steps mentioned below to connect MySQL
install connector using pip
pip install mysql-connector-python
or you can download the installer from https://dev.mysql.com/downloads/connector/python/
Use connect()
method of mysql connector python to connect to MySQL.pass the required argument to connect()
method. i.e. Host, username, password, and database name.
Create cursor
object from connection object returned by connect()
method to execute SQL queries.
close the connection after your work completes.
Example:
import mysql.connector
from mysql.connector import Error
try:
conn = mysql.connector.connect(host='hostname',
database='db',
user='root',
password='passcode')
if conn.is_connected():
cursor = conn.cursor()
cursor.execute("select database();")
record = cursor.fetchall()
print ("Your connected to - ", record)
except Error as e :
print ("Print your error msg", e)
finally:
#closing database connection.
if(conn.is_connected()):
cursor.close()
conn.close()
Reference - https://pynative.com/python-mysql-database-connection/
Important API of MySQL Connector Python
For DML operations - Use cursor.execute()
and cursor.executemany()
to run query. and after this use connection.commit()
to persist your changes to DB
To fetch data - Use cursor.execute()
to run query and cursor.fetchall()
, cursor.fetchone()
, cursor.fetchmany(SIZE)
to fetch data
for Python3.6 I found two driver: pymysql and mysqlclient. I tested the performance between them and got the result: the mysqlclient is faster.
below is my test process(need install python lib profilehooks to analyze time elapse:
raw sql: select * from FOO;
immediatly execute in mysql terminal: 46410 rows in set (0.10 sec)
pymysql (2.4s):
from profilehooks import profile
import pymysql.cursors
import pymysql
connection = pymysql.connect(host='localhost', user='root', db='foo')
c = connection.cursor()
@profile(immediate=True)
def read_by_pymysql():
c.execute("select * from FOO;")
res = c.fetchall()
read_by_pymysql()
mysqlclient (0.4s)
from profilehooks import profile
import MySQLdb
connection = MySQLdb.connect(host='localhost', user='root', db='foo')
c = connection.cursor()
@profile(immediate=True)
def read_by_mysqlclient():
c.execute("select * from FOO;")
res = c.fetchall()
read_by_mysqlclient()
here's the mysqlclient profile:
So, it seems that mysqlclient is much faster than pymysql