前言：
SQLite属于轻型数据库，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
一、简单操作SQLite数据库
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.
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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 |
1、简单的插入语句的使用
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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) |
2、简单的查询语句的使用
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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]) |
二、更新数据与删除
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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() |
三、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.
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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") |
四、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.
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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") print(temp) |
五、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.
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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() |
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原文链接：https://www.cnblogs.com/LyShark/p/12172674.html
