mysql-connector
MySQL officially provides the mysql-connector-python driver
-
install driver
python -m pip install mysql-connector -
Connect to the database to get the connection
import mysql.connector db = mysql.connector.connect( host="localhost", #ip user="root", #用户名 passwd="root",#密码 database="python_test",#连接数据库 auth_plugin='mysql_native_password' ) #获取游标 cursor = db.cursor()
Create database
cursor.execute("CREATE DATABASE python_test")
Output a list of all databases:
cursor.execute("SHOW DATABASES")
for x in cursor:
print(x)
"""
('basic_project',)
('ceam_mall2',)
('information_schema',)
('jwt-demo',)
('liugh',)
('mysql',)
('niu_b_xx_hou',)
"""
Create data table
cursor.execute("CREATE TABLE sites (name VARCHAR(255), url VARCHAR(255))")
Output all database tables:
cursor.execute("SHOW TABLES")
for x in cursor:
print(x)
#('sites',)
Primary key settings
cursor.execute("ALTER TABLE sites ADD COLUMN id INT AUTO_INCREMENT PRIMARY KEY")
Insert data
#sql
sql = "INSERT INTO sites (name, url) VALUES (%s, %s)"
#占位符插入数据
val = ("RUNOOB", "https://www.baidu.com")
#执行sql
cursor.execute(sql, val)
db.commit()
print(cursor.rowcount, "记录插入成功。")
Batch insert
- Batch insert
executemany()method, the second parameter of this method is a list of tuples, containing the data we want to insert:
sql = "INSERT INTO sites (name, url) VALUES (%s, %s)"
val = [
('Google', 'https://www.google.com'),
('Github', 'https://www.github.com'),
('Taobao', 'https://www.taobao.com'),
('stackoverflow', 'https://www.stackoverflow.com/')
]
#执行sql
cursor.executemany(sql, val)
#提交事务: 数据表内容有更新，必须使用到该语句
db.commit()
print(cursor.rowcount, "记录插入成功。")
If we want to get the ID of the data record after it is inserted, we can use the following code:
sql = "INSERT INTO sites (name, url) VALUES (%s, %s)"
val = ("Zhihu", "https://www.zhihu.com")
cursor.execute(sql, val)
db.commit()
print("1 条记录已插入, ID:", cursor.lastrowid)
Query data
cursor.execute("SELECT * FROM sites")
result = cursor.fetchall() # fetchall() 获取所有记录
for x in result:
print(x)
"""
('RUNOOB', 'https://www.runoob.com', 1)
('Google', 'https://www.google.com', 2)
('Github', 'https://www.github.com', 3)
('Taobao', 'https://www.taobao.com', 4)
('stackoverflow', 'https://www.stackoverflow.com/', 5)
('Zhihu', 'https://www.zhihu.com', 6)
"""
If we only want to read one piece of data, we can use the fetchone() method:
cursor.execute("SELECT * FROM sites")
result = cursor.fetchone()
print(result)
In order to prevent SQL injection attacks in database queries, we can use %s 占位符来转义查询的条件:
sql = "SELECT * FROM sites WHERE name = %s"
na = ("RUNOOB",)
cursor.execute(sql, na)
result = cursor.fetchall()
for x in result:
print(x)
delete
sql = "DELETE FROM sites WHERE name = %s"
na = ("stackoverflow",)
cursor.execute(sql, na)
db.commit()
print(cursor.rowcount, " 条记录删除")
renew
sql = "UPDATE sites SET name = %s WHERE name = %s"
val = ("Zhihu", "ZH")
cursor.execute(sql, val)
db.commit()
print(cursor.rowcount, " 条记录被修改")
close connection
#最后一定要关闭数据库连接
db.close()
Python连接MySQL报错：mysql.connector.errors.NotSupportedError: Authentication plugin ‘caching_sha2_password’ is not supported
- Add a statement (auth_plugin='mysql_native_password') and add the following code:
summary
commit()A commit transaction must be called after performing operations such as INSERT/UPDATE/DELETE ;- SQL placeholders for MySQL are
%s.
PyMySQL
PyMySQL is in Python3.x 版本中用于连接 MySQL 服务器的一个库, and Python2 uses mysqldb.
- PyMySQL follows
Python 数据库 API v2.0 规范and includes了 pure-Python MySQLclient libraries.
-
Install
pip3 install PyMySQL -
Database Connectivity
import pymysql # 打开数据库连接 db = pymysql.connect(host='localhost', user='root', password='root', database='python_test') # 使用 cursor() 方法创建一个游标对象 cursor cursor = db.cursor() # 使用 execute() 方法执行 SQL 查询 cursor.execute("SELECT VERSION()") # 使用 fetchone() 方法获取单条数据. data = cursor.fetchone() print ("Database version : %s " % data) # 关闭数据库连接 db.close()
Create database table
import pymysql
# 打开数据库连接
db = pymysql.connect(host='localhost',
user='testuser',
password='test123',
database='TESTDB')
# 使用 cursor() 方法创建一个游标对象 cursor
cursor = db.cursor()
# 使用 execute() 方法执行 SQL，如果表存在则删除
cursor.execute("DROP TABLE IF EXISTS EMPLOYEE")
# 使用预处理语句创建表
sql = """CREATE TABLE EMPLOYEE (
FIRST_NAME CHAR(20) NOT NULL,
LAST_NAME CHAR(20),
AGE INT,
SEX CHAR(1),
INCOME FLOAT )"""
cursor.execute(sql)
# 关闭数据库连接
db.close()
Database insert operation
import pymysql
# 打开数据库连接
db = pymysql.connect(host='localhost',
user='testuser',
password='test123',
database='TESTDB')
# 使用cursor()方法获取操作游标
cursor = db.cursor()
# SQL 插入语句
sql = """INSERT INTO EMPLOYEE(FIRST_NAME,
LAST_NAME, AGE, SEX, INCOME)
VALUES ('Mac', 'Mohan', 20, 'M', 2000)"""
try:
# 执行sql语句
cursor.execute(sql)
# 提交到数据库执行
db.commit()
except:
# 如果发生错误则回滚
db.rollback()
# 关闭数据库连接
db.close()
The above example can also be written in the following form:
import pymysql
# 打开数据库连接
db = pymysql.connect(host='localhost',
user='testuser',
password='test123',
database='TESTDB')
# 使用cursor()方法获取操作游标
cursor = db.cursor()
# SQL 插入语句
sql = "INSERT INTO EMPLOYEE(FIRST_NAME, \
LAST_NAME, AGE, SEX, INCOME) \
VALUES ('%s', '%s', %s, '%s', %s)" % \
('Mac', 'Mohan', 20, 'M', 2000)
try:
# 执行sql语句
cursor.execute(sql)
# 执行sql语句
db.commit()
except:
# 发生错误时回滚
db.rollback()
# 关闭数据库连接
db.close()
Database query operations
-
Python queries Mysql using the fetchone() method to obtain a single piece of data, and the fetchall() method to obtain multiple pieces of data.
- fetchone(): This method gets the next query result set. The result set is an object
- fetchall(): Receive all returned result lines.
- rowcount: This is a read-only property and returns the number of rows affected after executing the execute() method.
Query all data in the EMPLOYEE table whose salary field is greater than 1000:
import pymysql
# 打开数据库连接
db = pymysql.connect(host='localhost',
user='testuser',
password='test123',
database='TESTDB')
# 使用cursor()方法获取操作游标
cursor = db.cursor()
# SQL 查询语句
sql = "SELECT * FROM EMPLOYEE \
WHERE INCOME > %s" % (1000)
try:
# 执行SQL语句
cursor.execute(sql)
# 获取所有记录列表
results = cursor.fetchall()
for row in results:
fname = row[0]
lname = row[1]
age = row[2]
sex = row[3]
income = row[4]
# 打印结果
print ("fname=%s,lname=%s,age=%s,sex=%s,income=%s" % \
(fname, lname, age, sex, income ))
except:
print ("Error: unable to fetch data")
# 关闭数据库连接
db.close()
Database update operations
- Increment the AGE field in the TESTDB table with SEX of 'M' by 1:
import pymysql
# 打开数据库连接
db = pymysql.connect(host='localhost',
user='testuser',
password='test123',
database='TESTDB')
# 使用cursor()方法获取操作游标
cursor = db.cursor()
# SQL 更新语句
sql = "UPDATE EMPLOYEE SET AGE = AGE + 1 WHERE SEX = '%c'" % ('M')
try:
# 执行SQL语句
cursor.execute(sql)
# 提交到数据库执行
db.commit()
except:
# 发生错误时回滚
db.rollback()
# 关闭数据库连接
db.close()
Delete operation
- Delete all data in the data table EMPLOYEE with AGE greater than 20:
import pymysql
# 打开数据库连接
db = pymysql.connect(host='localhost',
user='testuser',
password='test123',
database='TESTDB')
# 使用cursor()方法获取操作游标
cursor = db.cursor()
# SQL 删除语句
sql = "DELETE FROM EMPLOYEE WHERE AGE > %s" % (20)
try:
# 执行SQL语句
cursor.execute(sql)
# 提交修改
db.commit()
except:
# 发生错误时回滚
db.rollback()
# 关闭连接
db.close()
Execute transaction
- Python DB API 2.0 transactions provide two methods
commit 或 rollback.
# SQL删除记录语句
sql = "DELETE FROM EMPLOYEE WHERE AGE > %s" % (20)
try:
# 执行SQL语句
cursor.execute(sql)
# 向数据库提交
db.commit()
except:
# 发生错误时回滚
db.rollback()
-
For databases that support transactions, in Python database programming, when the cursor is created, an invisible database transaction is automatically started.
- The commit() method commits all update operations of the current cursor, and the rollback() method rolls back all operations of the current cursor. Each method starts a new transaction.