Python 操作SQLite数据库的示例

SQLite，是一款轻型的数据库，是遵守ACID的关系型数据库管理系统，它包含在一个相对小的C库中。在很多嵌入式产品中使用了它，它占用资源非常的低，python 中默认继承了操作此款数据库的引擎 sqlite3 说是引擎不如说就是数据库的封装版，开发自用小程序的使用使用它真的大赞

简单操作SQLite数据库:创建 sqlite数据库是一个轻量级的数据库服务器,该模块默认集成在python中,开发小应用很不错.

import sqlite3# 数据表的创建conn = sqlite3.connect('data.db')cursor = conn.cursor()create = 'create table persion(' 'id int auto_increment primary key,' 'name char(20) not null,' 'age int not null,' 'msg text default null' ')'cursor.execute(create) # 执行创建表操作

简单操作SQLite数据库:简单的插入语句的使用

insert = 'insert into persion(id,name,age,msg) values(1,’lyshark’,1,’hello lyshark’);'cursor.execute(insert)insert = 'insert into persion(id,name,age,msg) values(2,’guest’,2,’hello guest’);'cursor.execute(insert)insert = 'insert into persion(id,name,age,msg) values(3,’admin’,3,’hello admin’);'cursor.execute(insert)insert = 'insert into persion(id,name,age,msg) values(4,’wang’,4,’hello wang’);'cursor.execute(insert)insert = 'insert into persion(id,name,age,msg) values(5,’sqlite’,5,’hello sql’);'cursor.execute(insert)data = [(6, ’王舞’,8, ’python’), (7, ’曲奇’,8,’python’), (9, ’C语言’,9,’python’)]insert = 'insert into persion(id,name,age,msg) values(?,?,?,?);'cursor.executemany(insert,data)

简单的查询语句的使用

select = 'select * from persion;'cursor.execute(select)#print(cursor.fetchall()) # 取出所有的数据select = 'select * from persion where name=’lyshark’;'cursor.execute(select)print(cursor.fetchall()) # 取出所有的数据select = 'select * from persion where id >=1 and id <=2;'list = cursor.execute(select)for i in list.fetchall(): print('字段1：', i[0]) print('字段2：', i[1])

简单的更新数据与删除

update = 'update persion set name=’苍老师’ where id=1;'cursor.execute(update)update = 'update persion set name=’苍老师’ where id>=1 and id<=3;'cursor.execute(update)delete = 'delete from persion where id=3;'cursor.execute(delete)select = 'select * from persion;'cursor.execute(select)print(cursor.fetchall()) # 取出所有的数据conn.commit() # 事务提交，每执行一次数据库更改的操作，就执行提交cursor.close()conn.close()

SQLite小试牛刀 实现用户名密码验证,当用户输入错误密码后,自动锁定该用户1分钟.

import sqlite3import re,timeconn = sqlite3.connect('data.db')cursor = conn.cursor()'''create = 'create table login(' 'username text not null,' 'password text not null,' 'time int default 0' ')'cursor.execute(create)cursor.execute('insert into login(username,password) values(’admin’,’123123’);')cursor.execute('insert into login(username,password) values(’guest’,’123123’);')cursor.execute('insert into login(username,password) values(’lyshark’,’1231’);')conn.commit()'''while True: username = input('username:') # 这个地方应该严谨验证,尽量不要让用户拼接SQL语句 password = input('passwor:') # 此处为了方便不做任何验证(注意:永远不要相信用户的输入) sql = 'select * from login where username=’{}’'.format(username) ret = cursor.execute(sql).fetchall() if len(ret) != 0: now_time = int(time.time()) if ret[0][3] <= now_time: print('当前用户{}没有被限制,允许登录...'.format(username)) if ret[0][0] == username:if ret[0][1] == password: print('用户 {} 登录成功...'.format(username))else: print('用户 {} 密码输入有误..'.format(username)) times = int(time.time()) + 60 cursor.execute('update login set time={} where username=’{}’'.format(times,username)) conn.commit() else:print('用户名正确,但是密码错误了...') else: print('账户 {} 还在限制登陆阶段,请等待1分钟...'.format(username)) else: print('用户名输入错误')

SQLite检索时间记录 通过编写的TimeIndex函数检索一个指定范围时间戳中的数据.

import os,time,datetimeimport sqlite3'''conn = sqlite3.connect('data.db')cursor = conn.cursor()create = 'create table lyshark(' 'time int primary key,' 'cpu int not null' ')'cursor.execute(create)# 批量生成一堆数据,用于后期的测试.for i in range(1,500): times = int(time.time()) insert = 'insert into lyshark(time,cpu) values({},{})'.format(times,i) cursor.execute(insert) conn.commit() time.sleep(1)'''# db = data.db 传入数据库名称# table = 指定表lyshark名称# start = 2019-12-12 14:28:00# ends = 2019-12-12 14:29:20def TimeIndex(db,table,start,ends): start_time = int(time.mktime(time.strptime(start,'%Y-%m-%d %H:%M:%S'))) end_time = int(time.mktime(time.strptime(ends,'%Y-%m-%d %H:%M:%S'))) conn = sqlite3.connect(db) cursor = conn.cursor() select = 'select * from {} where time >= {} and time <= {}'.format(table,start_time,end_time) return cursor.execute(select).fetchall()if __name__ == '__main__': temp = TimeIndex('data.db','lyshark','2019-12-12 14:28:00','2019-12-12 14:29:00')

SQLite提取数据并绘图 通过使用matplotlib这个库函数,并提取出指定时间的数据记录,然后直接绘制曲线图.

import os,time,datetimeimport sqlite3import numpy as npfrom matplotlib import pyplot as pltdef TimeIndex(db,table,start,ends): start_time = int(time.mktime(time.strptime(start,'%Y-%m-%d %H:%M:%S'))) end_time = int(time.mktime(time.strptime(ends,'%Y-%m-%d %H:%M:%S'))) conn = sqlite3.connect(db) cursor = conn.cursor() select = 'select * from {} where time >= {} and time <= {}'.format(table,start_time,end_time) return cursor.execute(select).fetchall()def Display(): temp = TimeIndex('data.db','lyshark','2019-12-12 14:28:00','2019-12-12 14:29:00') list = [] for i in range(0,len(temp)): list.append(temp[i][1]) plt.title('CPU Count') plt.plot(list, list) plt.show() if __name__ == '__main__': Display()

文章作者：lyshark文章出处：https://www.cnblogs.com/lyshark

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