python函数模拟mysql增删改查功能

import os
list1 = ['staff_id', 'name', 'age', 'phone', 'dept', 'enroll_date']
def staff_info():
    #获取员工信息生成器函数
    with open('staff_table.txt', 'r', encoding='utf-8') as f:
            for line in f :
             x =line.split(',')
             staff_dic = {k: v for (k, v) in zip(list1,x)}
             yield staff_dic

def select_func(select_content,start,middle,end):
    #查找函数
    if middle == '=':
        middle = '=='

    if select_content == '*':
        content = list1
    else:
        content = select_content.split(',')

    total_check = 0
    for i in staff_info():
        list = []
        for j in content:
            list.append(i[j])
        #查找需要列出的项
        if middle == 'like':
            l=len(end)
            if eval(i[start][:l] + '==' +end ):
                print(list)
                total_check+=1
        else:
            s = i[start]
            e = end
            if eval("s"+middle+"e"):
                print(list)
                total_check+=1

    print('相关查询共计%s'%total_check)

def insert_func(list):
    #添加功能函数，添加的内容以列表写入
    with open('staff_table.txt','r+',encoding='utf-8') as f:
        #判断手机号是否重复，若重复报错退出
        for line in f:
            if list[2] in line:
                print('err information')
                return
        #不重复的添加内容
        f.seek(0)
        info=f.readlines()
        staff_id=info[-1].split(',')
        staff_id=int(staff_id[0])+1
        f.seek(0,2)
        s=''
        for i in list:
            if type(i)==int:
                i=str(i)
            s=s+','+i
        f.write(str(staff_id)+s+'
')

def delete_func(staff_id):
    #删除信息函数
    with open('staff_table.txt','r+',encoding='utf_8') as f, 
         open('new.txt','w',encoding='utf-8') as f1:
        for line in f:
            if staff_id == line[0]:
                line=''
            f1.write(line)
    os.remove('staff_table.txt')
    os.rename('new.txt','staff_table.txt')

def modify_func(oldcontent,newcontent):
    #修改函数
    with open('staff_table.txt','r+',encoding='utf_8') as f, 
         open('new.txt','w',encoding='utf-8') as f1:
        for line in f:
            if oldcontent in line:
                line=line.replace(oldcontent,newcontent)
            f1.write(line)
    os.remove('staff_table.txt')
    os.rename('new.txt','staff_table.txt')

def run_func():
   #运行函数
   while 1:
       cmd=input('>>>: ')
       if cmd == 'quit':
           break
       else:
           cmd=cmd.split()
           if cmd[0] == 'select':
               end=cmd[-1]
               start=cmd[-3]
               middle=cmd[-2]
               select_content=cmd[1]
               select_func(select_content,start,middle,end)
           elif cmd[0] == 'insert':
               list=cmd[1].split(',')
               insert_func(list)
           elif cmd[0].lower() == 'update':
               oldcontent=cmd[-1]
               newcontent=cmd[5]
               modify_func(oldcontent,newcontent)
           elif cmd[0] == 'delete':
               staff_id=cmd[1]
               delete_func(staff_id)
           else:
               print('err input')

run_func()

staff_table.txt 里的内容：

1,Alex Li,22,13651054608,IT,2013-04-01
2,Jack Wang,30,13304320533,HR,2015-05-03
3,Rain Liu,25,1383235322,Sales,2016-04-22
4,Mack Cao,40,1356145343,HR,2009-03-01

因能力有限，命令格式请遵循下列说明

• 查询命令格式：select age,name from satff_table where dept == IT／age > 20/其他条件
• 修改命令格式：update staff_table set dept = market where where dept = IT
• 增加命令格式：insert mona, 15, 13693041938, IT, 2016-09-04
• 删除命令格式：delete 1