这次支持连接到后台的数据库，直接和数据库进行交互，实现基本的增删查改
#!/usr/bin/python3
# coding=utf-8
"""
***********************help document****************************************
Usage:
this is a simple student grades system,now is simple
when start the programming,you can do following operations
enter 'a' is to insert data into database
enter 'b' is to display all data in database
enter 'c' is to query the specify info in database
enter 'h' is to see this help dacument
enter 'd' is to delete someone student's info
enter nothing is to do nothing,you can enter again
simple help document is: "a--insert/b--display/c--query/h--help/d--delete/''--default"
Example:
please enter the OPcode: a then [enter]
***************************************************************************** """ #引入pymysql这个库用来连接数据据
import pymysql #打印帮助文档
def help_document():
print(__doc__) #在已有的数据库上创建数据库的表
def create_database():
#在mysql中创建数据库student_db
db = pymysql.connect('localhost', 'root', 'root')
name = 'student_db'
cursor = db.cursor()
cursor.execute('drop database if exists ' + name)
cursor.execute('create database if not exists ' + name)
db.close()
#在数据库student_db中创建数据表student_table
db = pymysql.connect('localhost', 'root', 'root', 'student_db')
cursor = db.cursor()
name = 'student_table'
cursor.execute('drop table if exists ' + name)
sql = """create table student_table(
name varchar(30) primary key not null,
age varchar(10),
id varchar(20),
grade varchar(10))"""
cursor.execute(sql)
db.commit()
db.close() #数据库的插入
def insert_db(name,age,id,grade):
db = pymysql.connect('localhost', 'root', 'root','student_db')
cursor = db.cursor()
sql = "insert into student_table (name,age,id,grade) values ('%s','%s','%s','%s')" % \
(name,age,id,grade)
cursor.execute(sql)
db.commit()
db.close() #打印数据库中所有数据
def display_db():
db = pymysql.connect('localhost', 'root', 'root', 'student_db')
cursor = db.cursor()
sql = "select * from student_table"
try:
cursor.execute(sql)
result = cursor.fetchall()
for row in result:
name = row[0]
age = row[1]
id = row[2]
grade = row[3]
print("name: '%s',age: '%s',id: '%s',grade: '%s'" % (name,age,id,grade))
print("that's all diaplayed!")
except:
print('nothing has been displayed...')
db.close() #数据库的查找
def query_db(name):
db = pymysql.connect('localhost', 'root', 'root', 'student_db')
cursor = db.cursor()
sql = "select * from student_table where name = '%s' " % name
try:
cursor.execute(sql)
result = cursor.fetchall()
for row in result:
name1 = row[0]
age1 = row[1]
id1 = row[2]
grade1 = row[3]
print("name: '%s',age: '%s',id: '%s',grade: '%s'" % \
(name1,age1,id1,grade1))
print('the query is over!')
except:
print('can not query data!')
db.close() #更新数据库
def update_db(name,age,id,grade):
db = pymysql.connect('localhost', 'root', 'root', 'student_db')
cursor = db.cursor()
sql = "update student_table set age = '%s',id = '%s',grade = '%s' where name = '%s'" % \
(age,id,grade,name)
try:
cursor.execute(sql)
db.commit()
print('updated successfully!')
except:
print('can not update data!')
db.close() #数据库的删除
def delete_db(name):
db = pymysql.connect('localhost', 'root', 'root', 'student_db')
cursor = db.cursor()
sql = "delete from student_table where name = '%s'" % name
try:
cursor.execute(sql)
db.commit()
print('delete the student info successfully!')
except:
print('delete failed...')
db.close() # 实现switch-case语句
class switch(object):
def __init__(self, value):
self.value = value
self.fall = False def __iter__(self):
"""Return the match method once, then stop"""
yield self.match
raise StopIteration def match(self, *args):
"""Indicate whether or not to enter a case suite"""
if self.fall or not args:
return True
elif self.value in args: # changed for v1.5, see below
self.fall = True
return True
else:
return False #建立一个学生类
class student:
#构造函数
def __init__(self, name, age, id, grade):
self.next = None
self.name = name
self.age = age
self.id = id
self.grade = grade
#每个学生可以输出自己的信息
def show(self):
print('name:', self.name, ' ', 'age:', self.age, ' ', 'id:', self.id, ' ', 'grade:', self.grade) #建立一个学生列表类
class stulist:
#构造函数
def __init__(self):
self.head = student('', 0, 0, 0)
#输出数据库中所有的数据
def display(self):
display_db()
#新增学生数据
def insert(self):
print('please enter:')
name = input('name:')
age = input('age:')
id = input('id:')
grade = input('grade:')
insert_db(name, age, id, grade) #查询学生数据
def query(self):
name = input('please enter the name you want to query:')
query_db(name) #删除学生数据
def delete(self):
name = input("please enter the student'name you want to delete:")
delete_db(name) #主函数，程序的入口
def main():
stulist1 = stulist()
user_input = input('please enter the OPcode:')
while user_input:
print("a--insert/b--display/c--query/h--help/d--delete/''--default")
for case in switch(user_input):
if case('a'): #按下'a'键
stulist1.insert()
user_input = input('please enter the OPcode:')
break
if case('b'): #按下'b'键
stulist1.display()
user_input = input('please enter the OPcode:')
break
if case('c'): #按下'c'键
stulist1.query()
user_input = input('please enter the OPcode:')
break
if case('d'): #按下'd'键
stulist1.delete()
user_input = input('please enter your OPcode:')
break
if case('h'): #按下'h'键
help_document()
user_input = input('please enter your OPcode:')
break
if case(): # default
print('please enter the OPcode...')
user_input = input('please enter the OPcode:')
break if __name__ == "__main__":
#第一次运行程序需要建立新的数据库,需要运行下面注释的一行代码，下次运行得将其注释掉
#create_database()
main()
结果效果图：
输入’h’查看帮助文档
输入’b’来查询数据库数据:
这个版本还是很粗糙，访问速度也很慢，如果以后还有时间的话，我会做一个界面出来，改进下和数据库的交互方式。
