要求：实现模拟sql登录，增删改查功能
#_*_conding:utf-8_*_ import os #登录验证部分 status_dic = { 'username': None, #设置一个登录用户 'status': False, #用于后面验证是否登录，登录状态 } def wrapper(func): #登录验证的装饰器 def inner1(): if status_dic['status']: ret = func() return ret else: print("请先进行登录") if login(): ret = func() return ret return inner1 def login(*args): #登录模块 with open("login.txt", encoding="utf-8", mode="r") as f: login_list = f.readlines() if args: #判断用户是否登录 status_dic['username'] = args[0] status_dic['status'] = True return True else: count = 0 while count < 3: if status_dic['status'] == False: username = input("请输入登录用户名:").strip() for i in login_list: if username == eval(i)["name"]: #对用户名进行检查，看是否存在，不存在直接走for循环的else判断，让用户进行注册 password = input("请登录用户密码:").strip() if password == eval(i)["password"]: #判断密码输入是否正确 print("login successfully") status_dic['username'] = username status_dic['status'] = True return sql_main() else: print("您还有%s次机会" % int(2 - count)) #3次机会验证，都错误会返回登录首页 count += 1 break else: print("检查用户名未注册...") y = input("是否注册(yes/no):").strip() if y == "yes" or y =="y": return register() elif y == "no" or y == "n": return home_page() else: print("输入错误...") else: print("错误太多次啦...") def register(): #注册模块 tag = True f1 = open("login.txt", encoding="utf-8", mode="r") login_list = f1.readlines() print("账号注册".center(50,"#")) while tag: username = input("请输入您注册的用户名:").strip() for i in login_list: if username == eval(i)["name"]: print("用户名已经存在,请重新输入") f1.close() break else: password = input("请输入您注册的密码:").strip() f2 = open("login.txt",encoding="utf-8",mode="a") f2.write("{} ".format({"name": username,"password": password})) tag = False print("注册成功") f2.close() return login(username, password) def log_out(): print("%s用户已注销" % status_dic['username']) status_dic['username'] = None status_dic['status'] = False def Quit_exit(): print("退出程序...") return exit() def home_page(): dic = { 1: login, 2: register, 3: sql_main, 4: log_out, 5: Quit_exit } while True: print('1:登录用户 2:注册用户 3:执行sql 4:注销 5:退出程序') bianhao = input("请输入选择的序列号:").strip() if bianhao.isdigit(): bianhao = int(bianhao) if 0 < bianhao <= 8: dic[bianhao]() else: print("输入编号不在范围内") else: print("输入的序列号只能是数字") #sql主程序，只有登录成功后才可以执行sql语句 s = ''' 支持的sql语法 1:insert insert into user values 张三,20,13412345678,BOSS 2:delete delete from user where id =6 3:update update user set name = Tom where id > 5 4:select select * from user select name,age from user where age > 2 select * from user where job='IT' select * from user where phone like 133 ''' @wrapper def sql_main(): print(' 33[0;31m%s 33[0m' % s) while True: sql = input("sql>").strip() if sql == 'exit': break if len(sql) == 0: continue sql_dic = sql_parse(sql) # print('main res is %s' % sql_dic) if len(sql_dic) == 0: print('sql语法不正确') continue res = sql_action(sql_dic) # print(' 33[41;1m%s 33[0m' % res[-1]) if type(res) is list: try: for i in res[-1]: if type(i) is str: print(i.strip()) else: print(i) print(" 共计查询出%s条数据" % len(res[1])) except TypeError: pass else: print(res) #sql处理部分 #第一部分：sql解析 def sql_parse(sql): #insert delete update select ''' 把sql字符串切分，提取命令信息，分发给具体的解析函数去解析 :param sql: :return: ''' parse_func = { 'insert': insert_parse, 'delete': delete_parse, 'update': update_parse, 'select': select_parse } #print('sql str is %s' % sql) sql_l = sql.split() func = sql_l[0] res = '' if func in parse_func: res = parse_func[func](sql_l) return res def insert_parse(sql_l): ''' 定义insert语句的语法结构，执行sql解析操作，返回sql_dic :param sql: :return: ''' sql_dic = { 'func': insert, 'insert': [], 'into': [], 'values': [] } return handle_parse(sql_l,sql_dic) def delete_parse(sql_l): ''' 定义delete语句的语法结构，执行sql解析操作，返回sql_dic :param sql: :return: ''' sql_dic = { 'func': delete, 'delete': [], 'from': [], 'where': [] } return handle_parse(sql_l,sql_dic) def update_parse(sql_l): ''' 定义update语句的语法结构，执行sql解析操作，返回sql_dic :param sql: :return: ''' sql_dic = { 'func': update, 'update': [], 'set': [], 'where': [] } return handle_parse(sql_l, sql_dic) def select_parse(sql_l): ''' 定义select语句的语法结构，执行sql解析操作，返回sql_dic :param sql: :return: ''' # print('from in the select_parse 33[41;1m%s 33[0m' % sql_l) sql_dic = { 'func':select, 'select': [], #查询字段 'from': [], #数据库.表 'where': [], #过滤条件 'limit': [] #limit条件 } return handle_parse(sql_l,sql_dic) def handle_parse(sql_l,sql_dic): ''' 执行sql解析操作，返回sql_dic :param sql_l: :param sql_dic: :return: ''' # print('sql_l is 33[40;1m%s033[0m sql_dic is 33[39;1m%s033[0m' %(sql_l,sql_dic)) tag = False for i in sql_l: if tag and i in sql_dic: tag = False if not tag and i in sql_dic: tag = True key = i continue if tag: sql_dic[key].append(i) if sql_dic.get('where'): sql_dic['where'] = where_parse(sql_dic.get('where')) #['id>4','and','id<10'] # print('from in the handle_parse sql_dic is 33[40;1m%s 33[0m' % sql_dic) return sql_dic def where_parse(where_l): #['id>','4','and','id','<10'] --> ['id>4','and','id<10'] res = [] key = ['and','or','not'] char = '' for i in where_l: if len(i) == 0:continue if i in key: #i为key当中存放的逻辑运算符 if len(char) != 0: char = three_parse(char) res.append(char) #char = 'id>4' ---> char = '['id','>','4']' res.append(i) char = '' else: char += i #'id>4' else: char = three_parse(char) res.append(char) #['id>4','and','id<=10'] --> [['id','>','4'],'and',['id','<=','10']] # print('from in the where_parse res is 33[40;1m%s 33[0m' % res) return res def three_parse(str_l): #'id<=10' ---> '['id','<=','10']' key = ['>','<','='] res = [] char = '' opt = '' tag = False for i in str_l: if i in key: tag = True if len(char) != 0: res.append(char) char = '' opt += i if not tag: char += i if tag and i not in key: tag = False res.append(opt) opt = '' char += i else: res.append(char) #新增解析like的功能 if len(res) == 1: res = res[0].split('like') res.insert(1,'like') # print('from in the three_parse res is 33[43;1m%s 33[0m' % res) return res #第二部分：sql执行 def sql_action(sql_dic): ''' 从字典sql_dic提取命令，分发给具体的命令执行函数去执行 :param sql_dic: :return: ''' return sql_dic.get('func')(sql_dic) def insert(sql_dic): #'insert': [], 'into': ['user'], 'values': ['a,23,11103213123,BOSS'] # print('insert %s' % sql_dic) count = -1 table = sql_dic.get('into')[0] f1 = open('%s' % table,'r',encoding='utf-8') for i in f1: if len(i.strip()) != 0: count += 1 f1.close() with open('%s' % table,'a+',encoding='utf-8') as f2: value = sql_dic.get('values')[0] if len(value.strip().split(',')) == 4: f2.write(' %s,%s' % (int(count+1),value)) print('insert successful') else: print('缺少字段') return value def delete(sql_dic): #'delete': [], 'from': ['user'], 'where': [['id', '>', '2']] # print('delete %s' % sql_dic) table = sql_dic.get('from')[0] table_bak = '%s.bak' % table with open('%s' % table, 'r', encoding='utf-8') as read_f,open('%s' % table_bak,'w') as write_f: lines = read_f.readline().strip() tag = True for line in read_f: if tag: write_f.write('%s '%lines) write_f.flush() tag = False dic = dict(zip(lines.split(','), line.split(','))) filter_res = logic_action(dic, sql_dic.get('where')) if not filter_res: write_f.write(line) write_f.flush() os.remove("%s" % table) os.rename("%s" % table_bak, "%s" % table) print('delete successful') return def update(sql_dic): #'update': ['user'], 'set': ['id', '=', "'TT'"], 'where': [['name', 'like', 'dog']]} #print('update %s' %sql_dic) table = sql_dic.get('update')[0] table_bak = '%s.bak' % table with open('%s' % table, 'r', encoding='utf-8') as read_f,open('%s' % table_bak,'w') as write_f: lines = read_f.readline().strip() tag = True for line in read_f: if tag: write_f.write('%s ' % lines) write_f.flush() tag = False dic = dict(zip(lines.split(','), line.split(','))) set = where_parse(sql_dic['set']) filter_res = logic_action(dic, sql_dic.get('where')) if not filter_res: write_f.write(line) else: old_list = lines.split(',') old_index = old_list.index(set[0][0]) old = line.split(',')[old_index] new = set[0][2] line = line.replace(old,new) write_f.write(line) write_f.flush() os.remove("%s" % table) os.rename("%s" % table_bak, "%s" % table) print('update successful') return def select(sql_dic): # print('from select sql_dic is %s' % sql_dic) #第一部分处理：from table = sql_dic.get('from')[0] f = open('%s' % table,'r',encoding='utf-8') lines = f.readline() #第二部分处理：where filter_res = where_action(f,sql_dic.get('where'),lines) # for i in filter_res: # print('filter res is %s' % i) #第三部分处理：limit limit_res = limit_action(filter_res,sql_dic.get('limit')) # for i in limit_res: # print('limit_res res is %s' % i) #第四部处理：select search_res = search_action(limit_res,sql_dic.get('select'),lines) f.close() return search_res def where_action(f,where_l,lines): # print('in where_action 33[41;1m%s 33[0m'%whele_l) res = [] if len(where_l) != 0: for i in f: dic = dict(zip(lines.strip().split(','),i.strip().split(','))) #文件中的一条记录和where_L全部内容进行比对 #逻辑判断 logic_res = logic_action(dic,where_l) if logic_res: res.append(i.split(',')) else: res = f.readlines() return res def logic_action(dic,where_l): res = [] # where_l = [['name', 'like', 'alex'], 'or', ['id', '<', '4'], 'or', ['id', '=', '1']] for i in where_l: if type(i) is list: i_k, opt, i_v = i if i[1] == '=': opt = '%s=' % i[1] if dic[i_k].isdigit(): dic_v = dic[i_k] else: dic_v = "'%s'" % dic[i_k] if opt != 'like': i = str(eval("%s%s%s" % (dic_v, opt, i_v))) else: if i_v in dic_v: i = 'True' else: i = 'False' res.append(i) res = eval(' '.join(res)) # print('== 33[45;1m%s 33[0m' %(res)) return res def limit_action(filter_res,limit_l): res = [] if len(limit_l) != 0: index = int(limit_l[0]) res = filter_res[0:index] else: res = filter_res return res def search_action(limit_res,select_l,lines): res = [] fileds_l = [] if select_l[0] == '*': res = limit_res fileds_l = lines.split(',') else: for i in limit_res: dic = dict(zip(lines.split(','),i)) r_l = [] fileds_l = select_l[0].split(',') for line in fileds_l: r_l.append(dic[line].strip()) res.append(r_l) # print('search_action r_l %s,%s' % (fileds_l,r_l)) return [fileds_l,res] if __name__ == '__main__': home_page()