Python3 Exercise: To the employee information file, to achieve additions and deletions to change the operation

1. Practice Requirements:

2. Data file (data_staff.txt)

1,alex li,22,13651054684, Yun, 2013-02-042,jack wang,20,13312331232,hr,2014-06-033,mike Cao,20,15504231232,Sales, 2013-05-064,jack chen,34,12404231232,hr,2011-02-015,lu haojie,21,15204231232, Yun ' An, 2013-08-12

3. Implementing the Code

A. Main program part: Use the dictionary type to implement the function call (key corresponding value is the function name, through the name () syntax can call function execution ), take advantage of the OS module remove () and rename () Implements the modification of the file after the old file is deleted and the new file is renamed.

1 ImportOS2msg_dict={3     '1': Search,4     '2': Add,5     '3':D elete,6     '4': Change,7     '5':'Exit'8 }9 Ten  whileTrue: One     Print(""" A 1: Query - 2: Add - 3: Delete the 4: Modify - 5: Exit -    """) -Choice=input ('Enter the serial number:') +     ifChoice not inchmsg_dict: -         Print("input Error, please re-enter") +         Continue A     ifint (choice) ==5: at exit () -     Else: -Msg_dict[choice] ()

B. Query function: The transformation from string to list is implemented mainly through the split () of common operation of String, andjoin () implements the conversion of list to string.

1 defSearch ():2      #Query Mode One: SELECT * from staff_table where age >=3      #Query Mode two: SELECT * from staff_table where dept = "IT"4      #Query Method Three: SELECT * from staff_table where enroll_date like ""5 6Data=input ('Enter your query information:')7Data=data.split (' ')8Con=data[7]9Asp=data[5]TenCount=0 OneWith open ('Data_staff','R', encoding='Utf-8') as F: A         ifasp==' Age': -              forLineinchF: -               ifInt (Line.split (',') [2]) >=int (con): the                  Print(line) -Count+=1 -         elifasp=='Dept': -              forLineinchF: +                ifLine.split (',') [4]inchCon: -                    Print(line) +Count + = 1 A         Else: at              forLineinchF: -                ifLine.split (',') [5].split ('-') [0]inchCon: -                    Print(line) -Count + = 1 -         Print('end of query, a total of information found to meet the conditions%d'% count)

C. Add function: read and write using ' r+ ' read/write mode (Note that write () in this way is appended to the end of the file)

1 defAdd ():2     #add Syntax: Name,age,phone,dept,enroll-date3Data=input ('Enter the employee information you want to add:')4List_data=data.strip (). Split (',')5List_all=[]6F=open ('Data_staff','r+')7      forLineinchF:8List_all.append (Line.strip (). Split (',') [3])9     ifLIST_DATA[2]inchList_all:Ten         Print("the user already exists") One f.close () A     Else: -          forLineinchF: - F.write (line) theStaff_id=str (Len (list_all) +1) - List_data.insert (0,str (staff_id)) -F.write ('\ n') -F.write (','. Join (list_data)) + f.close () -         Print('Add Success')

D. Delete function:

1 defRemove ():2     #Delete Syntax: delete from staff_table where staff_id =3Staff_id=input ("Enter the staff_id of the employee you want to delete:")4Staff_id=staff_id.strip (). Split (' ') [6]5F=open ('Data_staff','R')6F1=open ('New_data_staff','W')7      forLineinchF:8In_list=line.split (',')9         ifin_list[0]<staff_id:Ten F1.write (line) One         elifIn_list[0]>staff_id: AIN_LIST[0]=STR (int (in_list[0))-1) -F1.write (','. Join (in_list)) -         Else: the             Continue - f.close () - f1.close () -Os.remove ('Data_staff') +Os.rename ('New_data_staff','Data_staff') -     Print('Delete succeeded')

E. Modifying a function:

1 defChange ():2     #Modify Please enter (note space and no quotation marks): UPDATE staff_table SET dept = IT WHERE dept = Operations3Data=input ("Please enter the information you want to modify:")4Old=data.split (' ') [5]5New=data.split (' ') [9]6F=open ('Data_staff','R', encoding='Utf-8')7F1=open ('New_data_staff','W', encoding="Utf-8")8      forLineinchF:9         ifOldinchLine :TenLine=line.replace (old,new) One F1.write (line) A f.close () - f1.close () -Os.remove ('Data_staff') theOs.rename ('New_data_staff','Data_staff') -     Print('Modification succeeded')

Python3 Exercise: To the employee information file, to achieve additions and deletions to change the operation