SQL注入案例：防止拼接后端SQL语句

    import pymysql
    conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='mysql', db='user_table', charset='utf-8')
    cursor = conn.cursor()
    
    def query_key(key):
    sql = "SELECT name FROM user_info where key_id='{}'".format(key)
    cursor.execute(sql)
    fet = cursor.fetchone()
    
    if not fet:
        result = "Not Found"
    else:
        result = fet[0]
    
    print(result)

    key = 10
    query_key(key)
    # SELECT name FROM use