Python操作MySql --Python

Python版本：v3.7

模块：pymysql

1、连接数据库

connectDB.py：

# encoding:utf-8import pymysql

host = ‘localhost‘  # 主机username = ‘root‘  # 用户名pwd = ‘nxl123‘  # 密码dbName = ‘testdb‘  # 数据库名# 打开数据库连接db = pymysql.connect(host, username, pwd, dbName)# 通过cursor方法获取操作游标cursor = db.cursor()# sql语句sql = ‘SELECT VERSION()‘# 执行sql语句cursor.execute(sql)# 使用fetchone方法获取一个查询结果集data = cursor.fetchone()# 输出结果集print(‘db version:%s‘ % data)# 关闭数据库连接db.close()

2、创建表

createTables.py：

# encoding:utf-8import pymysql

host = ‘localhost‘  # 主机username = ‘root‘  # 用户名pwd = ‘nxl123‘  # 密码dbName = ‘testdb‘  # 数据库名# 打开数据库连接db = pymysql.connect(host, username, pwd, dbName)# 通过cursor方法获取操作游标cursor = db.cursor()# 执行sql语句,如果存在stu和sex表，就将其删除cursor.execute(‘DROP TABLE IF EXISTS stu‘)cursor.execute(‘DROP TABLE IF EXISTS sex‘)# sql语句，创建stu表sql = ‘‘‘CREATE TABLE stu(      stuId SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT,      stuNo VARCHAR(20) NOT NULL UNIQUE KEY,      stuName VARCHAR(10) NOT NULL,      age SMALLINT UNSIGNED NOT NULL,      sexId SMALLINT UNSIGNED NOT NULL)‘‘‘sql2 = ‘‘‘CREATE TABLE sex(      id SMALLINT UNSIGNED PRIMARY KEY,      sex ENUM(‘男‘,‘女‘) NOT NULL)‘‘‘# 执行sql、sql2语句cursor.execute(sql)cursor.execute(sql2)# 关闭数据库连接db.close()

3、插入数据

insertData.py：

# encoding:utf-8import pymysql

host = ‘localhost‘  # 主机username = ‘root‘  # 用户名pwd = ‘nxl123‘  # 密码dbName = ‘testdb‘  # 数据库名db = pymysql.connect(host, username, pwd, dbName)# 通过cursor方法获取操作游标cursor = db.cursor()# sql语句# sql = ‘‘‘INSERT stu(stuNo,stuName,age,sexId) VALUES(‘2015011070‘,‘Thanlon‘,22,1) ‘‘‘# sql = ‘‘‘INSERT stu(stuNo,stuName,age,sexId) VALUES(‘2015011071‘,‘Maria‘,20,2) ‘‘‘# sql = ‘‘‘INSERT sex(id,sex) VALUES(1,‘男‘)‘‘‘sql = ‘‘‘INSERT sex(id,sex) VALUES(2,‘女‘)‘‘‘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()

stu 表：

sex 表：

4、删除数据

deleteData.py：

# encoding:utf-8import pymysql

host = ‘localhost‘  # 主机username = ‘root‘  # 用户名pwd = ‘nxl123‘  # 密码dbName = ‘testdb‘  # 数据库名# 打开数据库连接db = pymysql.connect(‘localhost‘, username, pwd, dbName)# 通过cursor方法获取操作游标cursor = db.cursor()sql = "DELETE FROM stu WHERE age>‘%d‘" % (20)try:    # 执行sql语句    cursor.execute(sql)    # 提交到数据库执行    db.commit()except:    # 语句产生异常时打印提示信息    print(‘更新数据时出现异常！‘)finally:    # 关闭数据库连接    db.close()

stu表：(删除数据后的stu表)

5、查询数据

selectData.py：

# encoding:utf-8import pymysql

host = ‘localhost‘  # 主机username = ‘root‘  # 用户名pwd = ‘nxl123‘  # 密码dbName = ‘testdb‘  # 数据库名# 打开数据库连接db = pymysql.connect(host, username, pwd, dbName)# 通过cursor方法获取操作游标cursor = db.cursor()# sql = ‘‘‘SELECT *FROM stu‘‘‘sql = ‘‘‘SELECT stuID,stuNo,stuName,age,x.sex FROM sex AS x INNER JOIN stu AS s ON s.sexId = x.id‘‘‘try:    # 执行sql语句    cursor.execute(sql)    # results接收全部的返回结果行    results = cursor.fetchall()    # print(results)    # 返回执行execute方法后影响的行数    results_count = cursor.rowcount    # 打印输出影响的行数    print(‘execute()方法执行后影响的行数:%d行‘ % results_count)    # 遍历结果集    for row in results:        stuID = row[0]        stuNo = row[1]        stuName = row[2]        age = row[3]        sex = row[4]        # 打印查询结果        print(stuID, stuNo, stuName, age, sex)except:    print(‘获取数据出现异常！‘)finally:    # 关闭数据库连接    db.close()

6、修改数据

updateData.py：

# encoding:utf-8import pymysql

host = ‘localhost‘  # 主机username = ‘root‘  # 用户名pwd = ‘nxl123‘  # 密码dbName = ‘testdb‘  # 数据库名# 打开数据库连接db = pymysql.connect(host, username, pwd, dbName)# 通过cursor方法获取操作游标cursor = db.cursor()

# 将性别为男的学生年龄加1

sql = ‘‘‘UPDATE stu SET age=age+1 WHERE sexId=1‘‘‘try:    # 执行语句    cursor.execute(sql)    # 提交到数据库执行    db.commit()except:    print(‘更新数据时出现异常！‘)finally:    # 关闭数据库连接    db.close()

执行语句前stu表信息：

执行语句后stu表信息：

原文地址：https://www.cnblogs.com/qikeyishu/p/10358032.html