python连接mysql数据库——＜一＞

import pandas as pd
import pymysql
 
class DataBase(object):
    
    def __init__(self,name,password):
        # 创建数据库连接
        self.conn = pymysql.connect('localhost','root',str(password),str(name),charset='utf8mb4')
        # 创建cursor对象
        self.cursor = self.conn.cursor()
        
    def __enter__(self):
        return self.cursor  # 返回cursor对象，且这个cursor对象会被赋给with语句中as后面的变量
    
    def __exit__(self,exc_type,exc_value,traceback):
        self.cursor.close()    # 关闭游标对象
        self.conn.close()      # 断开数据库连接
        
 
def main():
    with DataBase('mysql',123456) as db:
        db.execute("select help_topic_id,help_keyword_id from help_relation")   # 执行sql语句
        content = db.fetchall()  # 获取数据(db中保存着查询结果集)
        df = pd.DataFrame(list(content))  # 将从数据库中查询出的数据放入DataFrame对象中
    return df
    
        
if __name__ == '__main__':
    df = main()
 
new_cols = ['host','user']
df.columns = new_cols
print(df.head(20))

运行成功：