pymsql简单的使用

不废话直接上代码：

import pymysql

class MysqlConnection:
    '''
    单例模式获取数据库链接实例
    '''
    _instance = None
    def __new__(cls,  *args, **kwargs):
        if not cls._instance:
            cls._instance = pymysql.connect( *args, **kwargs)
        return cls._instance

if __name__ == '__main__':
    conn = MysqlConnection(db='spider_data',user='root',password='root',host='127.0.0.1')
    # 获取游标
    cursor = conn.cursor()
    sql = 'select {} from {} limit {}'.format(
        ','.join(('img_url','link','title')),
        'chinaz',
        '0,4'
    )
    # 执行sql语句,返回受影响的行数
    print(cursor.execute(sql))
    # 读取一条数据
    print(cursor.fetchone())
    # 读取多条，结果是一个tupe类型
    print(cursor.fetchmany(2))
    # 游标置零
    cursor.rownumber = 0
    # 读取全部
    print(cursor.fetchall())
    # 插入数据
    sql = 'insert into {}({}) values({})'.format('chinaz', ','.join(('img_url', 'link', 'title')),'\"img1\",\"link1\",\"title1\"')
    try:
        cursor.execute(sql)
        # 提交保存到数据库中
        conn.commit()
    except:
        # 回滚
        conn.rollback()

    # 关闭游标
    cursor.close()
    # 关闭和数据库的连接
    conn.close()

# 执行后的打印结果
"""
4
('http://topimg.chinaz.com/WebSiteimages/pkueducn/56abaa19-b68f-4338-b710-561168d3686e_2016_s.png', 'http://top.chinaz.com/Html/site_pku.edu.cn.html', '北京大学')
(('http://topimg.chinaz.com/WebSiteimages/fudaneducn/d95f4aa6-8fdc-4b3d-b2d7-94f4be58de77_2016_s.png', 'http://top.chinaz.com/Html/site_fudan.edu.cn.html', '复旦大学'), ('http://topimg.chinaz.com/WebSiteimages/wwwscueducn/79382c04-0541-4779-b05a-936a518a6cc8_2015_s.png', 'http://top.chinaz.com/Html/site_scu.edu.cn.html', '四川大学'))
(('http://topimg.chinaz.com/WebSiteimages/pkueducn/56abaa19-b68f-4338-b710-561168d3686e_2016_s.png', 'http://top.chinaz.com/Html/site_pku.edu.cn.html', '北京大学'), ('http://topimg.chinaz.com/WebSiteimages/fudaneducn/d95f4aa6-8fdc-4b3d-b2d7-94f4be58de77_2016_s.png', 'http://top.chinaz.com/Html/site_fudan.edu.cn.html', '复旦大学'), ('http://topimg.chinaz.com/WebSiteimages/wwwscueducn/79382c04-0541-4779-b05a-936a518a6cc8_2015_s.png', 'http://top.chinaz.com/Html/site_scu.edu.cn.html', '四川大学'), ('http://topimg.chinaz.com/WebSiteimages/wwwtsinghuaeducn/49499b0d-fc15-4be3-8ffe-a52d26469321_2017_s.png', 'http://top.chinaz.com/site_www.tsinghua.edu.cn.html', '清华大学'))

"""