python 操作 MySQL

source coding

#!/usr/bin/env python
# coding=utf-8

import pymysql


def connect_db():
    print('连接到mysql服务器...')
    db = pymysql.connect(host="localhost", user="root", password="****20*0", database="world")
    print('连接上了')
    return db


def create_table(db):
    cursor = db.cursor()
    cursor.execute("DROP TABLE IF EXISTS Student")
    sql = """CREATE TABLE Student(
             ID CHAR(10) NOT NULL,
             Name CHAR(8),
             Grade INT )"""
    cursor.execute(sql)


def insertdb(db):
    cursor = db.cursor()

    sql = """INSERT INTO Student
         VALUES ('001', 'CZQ', 70),
                ('002', 'LHQ', 80),
                ('003', 'MQ', 90),
                ('004', 'WH', 80),
                ('005', 'HP', 70),
                ('006', 'YF', 66),
                ('007', 'TEST', 100)"""
    try:
        # 执行sql语句
        cursor.execute(sql)
        # 提交到数据库执行
        db.commit()
    except:
        # Rollback in case there is any error
        print
        '插入数据失败!'
        db.rollback()


def querydb(db):
    # 使用cursor()方法获取操作游标
    cursor = db.cursor()

    # SQL 查询语句
    # sql = "SELECT * FROM Student \
    #    WHERE Grade > '%d'" % (80)
    sql = "SELECT * FROM Student"
    try:
        # 执行SQL语句
        cursor.execute(sql)
        # 获取所有记录列表
        results = cursor.fetchall()
        for row in results:
            ID = row[0]
            Name = row[1]
            Grade = row[2]
            # 打印结果
            print("ID: %s, Name: %s, Grade: %d" % \
                  (ID, Name, Grade))
    except:
        print("Error: unable to fecth data")


def deletedb(db):
    # 使用cursor()方法获取操作游标
    cursor = db.cursor()

    # SQL 删除语句
    sql = "DELETE FROM Student WHERE Grade = '%d'" % (100)

    try:
        # 执行SQL语句
        cursor.execute(sql)
        # 提交修改
        db.commit()
    except:
        print('删除数据失败!')
        # 发生错误时回滚
        db.rollback()


def updatedb(db):
    # 使用cursor()方法获取操作游标
    cursor = db.cursor()

    # SQL 更新语句
    sql = "UPDATE Student SET Grade = Grade + 3 WHERE ID = '%s'" % ('003')

    try:
        # 执行SQL语句
        cursor.execute(sql)
        # 提交到数据库执行
        db.commit()
    except:
        print('更新数据失败!')
        # 发生错误时回滚
        db.rollback()


def closedb(db):
    db.close()


def main():
    db = connect_db()  # 连接MySQL数据库

    create_table(db)  # 创建表
    insertdb(db)  # 插入数据
    print('\n插入数据后:')
    querydb(db)
    deletedb(db)  # 删除数据
    print('\n删除数据后:')
    querydb(db)
    updatedb(db)  # 更新数据
    print('\n更新数据后:')
    querydb(db)

    closedb(db)  # 关闭数据库


if __name__ == '__main__':
    main()

(venv) C:\Users\zhou\PycharmProjects\data_wrangling\My Scripts>"C:/Users/zhou/PycharmProjects/data_wrangling/My Scripts/connmysql.py"
连接到mysql服务器...
连接上了

插入数据后:
ID: 001, Name: CZQ, Grade: 70
ID: 002, Name: LHQ, Grade: 80
ID: 003, Name: MQ, Grade: 90
ID: 004, Name: WH, Grade: 80
ID: 005, Name: HP, Grade: 70
ID: 006, Name: YF, Grade: 66
ID: 007, Name: TEST, Grade: 100

删除数据后:
ID: 001, Name: CZQ, Grade: 70
ID: 002, Name: LHQ, Grade: 80
ID: 003, Name: MQ, Grade: 90
ID: 004, Name: WH, Grade: 80
ID: 005, Name: HP, Grade: 70
ID: 006, Name: YF, Grade: 66

更新数据后:
ID: 001, Name: CZQ, Grade: 70
ID: 002, Name: LHQ, Grade: 80
ID: 003, Name: MQ, Grade: 93
ID: 004, Name: WH, Grade: 80
ID: 005, Name: HP, Grade: 70
ID: 006, Name: YF, Grade: 66