本文重点在于演示Python对SQLite数据库的操作,以及命令行式菜单的工作原理和实现。
首先使用SQLite Database Browser创建SQLite数据库data.db,然后创建一个数据表addressList,最后在数据表addressList中创建字段id(INTEGER PRIMARY KEY类型)、name(TEXT类型)、sex(TEXT类型)、age(NUMERIC类型)、department(TEXT类型)、telephone(TEXT类型)和qq(TEXT类型)。然后编写下面的程序,运行后根据不同的命令进入查看、删除、增加等不同的功能或退出程序。
import sqlite3
def menu(): '''本函数用来显示主菜单''' usage = ('\tL/l: List all the information.', '\tD/d: Delete the information of certain people.', '\tA/a: Add new information for a new people', '\tQ/q: Exit the system.', '\tH/h: Help, view all commands.') print('Main menu'.center(70, '=')) for u in usage: print(u)
def doSql(sql): '''用来执行SQL语句,尤其是INSERT和DELETE语句''' conn = sqlite3.connect('data.db') cur = conn.cursor() cur.execute(sql) conn.commit() conn.close() def add(): '''本函数用来接收用户输入,检查格式,然后插入数据库''' print('Add records'.center(70, '=')) #获取输入,只接受正确格式的数据 while True: record = input('Please input name, sex, age, department, telephone, qq(Q/q to return):\n') #输入q或Q表示退出,结束插入记录的过程,返回主菜单 if record in ('q', 'Q'): print('\tYou have stopped adding record.') return #正确的格式应该恰好包含5个英文逗号 if record.count(',') != 5: print('\tformat or data error.') continue else: name, sex, age, department, telephone, qq = record.split(',') #性别必须是F或M if sex not in ('F', 'M'): print('\tsex must be F or M.') continue #手机号和qq必须是数字字符串 if (not telephone.isdigit()) or (not qq.isdigit()): print('\ttelephone and qq must be integers.') continue #年龄必须是介于1到130之间的整数 try: age = int(age) if not 1<=age<=130: print('\tage must be between 1 and 130.') continue except: print('\tage must be an integer.') continue sql = 'INSERT INTO addressList(name,sex,age,department,telephone,qq) VALUES("' sql = sql + name + '","' + sex + '",' + str(age) + ',"' + department + '","' sql = sql + telephone + '","' + qq + '")' doSql(sql) print('\tYou have add a record.')
def exist(recordId): '''本函数用来测试数据表中是否存在recordId的id''' conn = sqlite3.connect('data.db') cur = conn.cursor() cur.execute('SELECT COUNT(id) from addressList where id=' + str(recordId)) c = cur.fetchone()[0] conn.close() return c!=0
def remove(): '''本函数用来接收用户输入的id号,并删除数据库中该id对应的记录''' print('Delete records'.center(70, '=')) while True: #输入q或Q,返回上一级目录 x = input('Please input the ID to delete(Q/q to return):\n') if x in ('q', 'Q'): print('\tYou have stopped removing record.') return
#要删除的id必须是数字,并且已存在于数据库中 try: recordId = int(x) if not exist(recordId): print('\tThis id does not exists.') else: sql = 'DELETE FROM addressList where id=' + x doSql(sql) print('\tYou have deleted a record.') except: print('\tid must be an integer') def listInformation(): '''本函数用来查看所有记录''' sql = 'SELECT * FROM addressList ORDER BY id ASC' conn = sqlite3.connect('data.db') cur = conn.cursor() cur.execute(sql) result = cur.fetchall() if not result: print('\tDatabase has no record at this time.') else: #格式化输出所有记录 print('All records'.center(70, '=')) print('Id Name Sex Age Department Telephone QQ') for record in result: print(str(record[0]).ljust(6), end='') print(record[1].ljust(8), end='') print(record[2].ljust(7), end='') print(str(record[3]).ljust(7), end='') print(record[4].ljust(18), end='') print(record[5].ljust(13), end='') print(record[6]) print('='*30) conn.close() def main(): '''系统主函数''' print('Welcome to the addresslist manage system.') menu() while True: command = input('Please choose a command:') if command in ('L', 'l'): listInformation() elif command in ('D', 'd'): remove() menu() elif command in ('A', 'a'): add() menu() elif command in ('Q', 'q'): break elif command in ('H', 'h'): menu() else: print('\tYou have input a wrong command.')
#调用主函数,启动系统 main()