文件查询 select name,age where age>22

# 员工信息表： 完善代码，背下来给代码加注释
column_dic = {'id': 0, 'name': 1, 'age': 2, 'phone': 3, 'job': 4}    # 将文件每一列的名字和数字的对应关系
# --条件--筛选
def filter_handler(operate, col):  # >, age>22
    """
    精心筛选工作
    :param opertate: 用户要进行的操作是><= like
    :param col: 用户输入的where条件
    :return: 被选中的所有行组成的列表，其中每一行都是一个列表
    """
    select_lst = []   # 被选中的列表
    col, val = col.split(operate)  # age,22='>','age>22'
    col = col.strip()  # age
    val = val.strip()  # 22
    judge = 'int(line_lst[column_dic[col]]) %s int(val)'%operate if operate == '<' or operate == '>' else 'line_lst[column_dic[col]] %s val' %operate
    f = open('file', encoding='utf-8')
    for line in f:
        line_lst = line.strip().split(',')  # [id, name, 25, phone, job]
        if eval(judge):
            select_lst.append(line_lst)
    f.close()
    return select_lst
# 展示符合条件的员工信息
def get_selected_line(con):  # con = 'age>22'
    """
    获取所有要查找的行，并将每一行作为一个列表项存储在select_lst中
    :param con:
    :return: 存储了符合条件的行的列表
    """
    if '>' in con:
        selected_lst = filter_handler('>', con)
    elif '<' in con:
        selected_lst = filter_handler('<', con)
    elif '=' in con:
        selected_lst = filter_handler('==', con.replace('=', '=='))
    elif 'like' in con:
        selected_lst = filter_handler('in', con)
    return selected_lst
# 读取文件 ---将文件中的内容整理
def get_show_lst(col_condition):
    """
    获取要展示的列名
    :param col_condition: 用户输入的select条件
    :return: 列名组成的字典
    """
    col_info_lst = col_condition.strip().split('select')
    col_info_lst = [col_info_item for col_info_item in col_info_lst if col_info_item.strip()]
    if col_info_lst:
        col_info = col_info_lst[0].strip()
        if '*' == col_info:
            return column_dic.keys()
        elif col_info:
            ret = col_info.split(',')
            return [item.strip() for item in ret]
        else: print(col_info)
# 读取用户的信息 ---分析信息
def show(selected_lst, show_lst):
    """
    展示符合条件的内容
    :param selected_lst: 符合条件的行的列表
    :param show_lst: 所有要展示的字段
    :return: None
    """
    for selected_item in selected_lst:
        for col in show_lst:
            print(selected_item[column_dic[col]], end='')
        print()
condition = input(">>>")  # 接收用户的指令
# 解析用户的指令
ret = condition.split('where')  # ['select name, age', 'age>22']
con = ret[1].strip()  # 'age>22'
# 根据select条件解析用户需要展示的内容
show_lst = get_show_lst(ret[0])  # '[NAME,AGE]' = 'select name,age'
# 根据where条件解析用户想查找的内容
select_lst = get_selected_line(con)  # selected_lst中存储了所有符合条件的内容
# 将符合条件的内容按照用户的需求展示出来
show(select_lst, show_lst)  # 显示