python学习day5

# _*_ coding:utf-8 _*_"""模拟数据库：表内容：1,Alex,22,13651054608,IT2,Egon,23,13304320533,Tearcher3,ding,23,18311028091,IT表结构：KEYS = ["id", "name", "age", "phone", "job"]只有一个信息表，表名：table增，语法：add from table ding,23,18311028091,IT删，语法：del from table where id=3改，语法：update table set age = 23 where name=ding查，语法：select from table where age=22          select * from table where age=22          select * from table"""import osdb_file = "table"KEYS = ["id", "name", "age", "phone", "job"]def print_log(msg, log_type="info"):    if log_type == "info":        print(msg)    elif log_type == "error":        print("\033[31;1m%s\033[0m" % msg)def load_db(db_file):    """    加载员工信息表，加载成字典格式    :param db_file:    :return:    """    info = {}    for i in KEYS:        info[i] = []    with open(db_file, encoding="utf-8") as f:        for line in f:            cust_id, name, age, phone, job = line.split(",")            info["id"].append(cust_id)            info["name"].append(name)            info["age"].append(age)            info["phone"].append(phone)            info["job"].append(job)        return infoDATA = load_db(db_file)def method_gt(column, condtion_val):    """    ">"方法    :param column:listing    :param val:值    :return:    """    user_info = []    for index,val in enumerate(DATA[column]):        if float(val) > float(condtion_val):            record = []            for col in KEYS:               record.append(DATA[col][index])            user_info.append(record)    return user_infodef method_lt(column, condtion_val):    """    "<"方法    :param column:    :param condtion_val:    :return:    """    user_info = []    for index,val in enumerate(DATA[column]):        if float(val) < float(condtion_val):            record = []            for col in KEYS:               record.append(DATA[col][index])            user_info.append(record)    return user_infodef method_eq(column, condtion_val):    """    "="方法    :param column:    :param condtion_val:    :return:    """    user_info = []    for index,val in enumerate(DATA[column]):        if val == condtion_val:            record = []            for col in KEYS:               record.append(DATA[col][index])            user_info.append(record)    return user_infodef method_like(column, condtion_val):    """    "like"方法    :param column:    :param condtion_val:    :return:    """    user_info = []    for index,val in enumerate(DATA[column]):        if condtion_val in val:            record = []            for col in KEYS:               record.append(DATA[col][index])            user_info.append(record)    return user_infodef way_where(clause):    """    解析where条件，并过滤数据    :param clause:    :return:    """    method = {        ">": method_gt,        "<": method_lt,        "=": method_eq,        "like": method_like    }    for method_key, method_func in method.items():        if method_key in clause:            column, val = clause.split(method_key)            user_data = method_func(column.strip(), val.strip())            return user_data    else:        print_log("语法错误：where条件只支持[>,<,=,like]", "error")def sql_parser(choise):    """    解析sql语句    :param choise:    :return:    """    way_list = {        "select":way_select,        "add":way_add,        "update":way_update    }    if choise.split()[0] in ("add", "del", "update", "select"):        if "where" in choise:            query_clause, where_clause = choise.split("where")            way_where(where_clause)            user_data = way_where(where_clause)        else:            user_data = []            for index,cust_id in enumerate(DATA["id"]):                data = []                for col in KEYS:                    data.append(DATA[col][index])                user_data.append(data)            query_clause = choise        choise_action = choise.split()[0]        if  choise_action in way_list:            way_list[choise_action](user_data,query_clause)        elif choise.split()[0] == "del":            way_delete(user_data,choise)    else:        print_log(            "语法错误:[add\\del\\update\\select] from [table] [where] [listing] [>,<,=,like] [val]\n",            "error")def way_add(date_set,query_clause):    """    对员工信息表添加数据    语法：add from table ding,23,18311028091,IT    :param date_set:    :param query_clause:    :return:    """    choise_way = query_clause.split("from")[0].strip()    choise_val = query_clause.split(db_file)[1].strip()    if choise_way == "add" and len(choise_val) > 1:        with open(db_file,encoding="utf-8",mode="a") as f1:            choise_id = id + 1            choise_id_1 = str(choise_id)            f1.write(choise_id_1)            f1.write(",")            f1.write(choise_val)            f1.close()            print("添加%s成功！"% choise_val)def way_select(data_set,query_clause):    """    解析查询语句并从data_set打印指定的列    语法：select from table where age=22          select * from table where age=22          select * from table    :param date_set:    :param query_clause:    :return:    """    columns = query_clause.split("from")[0][6:].split(",")    cols = [i.strip() for i in columns]    if '*' in cols[0]:        print(data_set)    else:        format_data_set = []        for listing in data_set:            col_vals = []  #把要打印的字段放在这个列表里            for col in cols:                col_index = KEYS.index(col) #拿到每条记录的索引和对应的值                col_vals.append( listing[col_index] )            format_data_set.append(col_vals)        for i in format_data_set:            print(i)def read():    with open(db_file, encoding="utf-8", mode="r") as f:        lines = f.readlines()        last_line = lines[-1]        last_id = last_line[0]        last_id_1 = int(last_id)        f.close()    return last_id_1id = read()def way_delete(data_set,choise):    """    根据"id"号删除整行数据    del from table where id=3    :param date_set:    :param query_clause:    :return:    """    columns = choise.split("where")[1].split("=")[1]    columns_id = int(columns)    if columns in DATA["id"]:        with open(db_file,encoding="utf-8",mode="r") as f:            user_info = []            for i in f:                r = i.strip().split("\n")                user_info.append(r)            user_info.pop(columns_id-1)            f.close()        with open("%s.new" % db_file, encoding="utf-8", mode="w") as f1:            for w in user_info:                str = ",".join(w)                f1.write(str+"\n")            f1.close()            os.remove(db_file)            os.rename("%s.new" % db_file, db_file)            print("删除数据成功！")    else:        print_log("输入有误！","error")        #with open(db_file,encoding="utf-8",mode="w") as f:def way_update(data_set,query_clause):    """    语法：update table set age = 23 where name=ding    :param date_set:    :param query_clause:    :return:    """    update_info = query_clause.split("set")    if len(update_info) > 1:        col_name,new_val = update_info[1].strip().split("=")        for matched_row in data_set:            cust_id = matched_row[0]            cust_id_index = DATA["id"].index(cust_id)            DATA[col_name][cust_id_index] = new_val        save_db()        print("update" "  "  +col_name+ "=" +new_val+ "  ""数据成功！")    else:        print_log("语法错误：未检测到set关键字!","error")def save_db():    """    把修改 在内存中的数据存到硬盘    :return:    """    with open("%s.new"%db_file,encoding="utf-8",mode="w") as f1:        for index,cust_id in enumerate(DATA["id"]):            row = []            for col in KEYS:                row.append( DATA[col][index])            f1.write(",".join(row))        f1.close()        os.remove(db_file)        os.rename("%s.new"% db_file,db_file)def main():    """    次函数是用户输入sql语句，调用sql语句方法。    :return:    """    while True:        choise = input("SQL：").strip()        if not choise:            print("输入不能为空，请从新输入。")            continue        sql_parser(choise.strip())main()