SQLite，是一款輕型的數據庫，是遵守ACID的關系型數據庫管理系統，它包含在一個相對小的C庫中。在很多嵌入式產品中使用了它，它占用資源非常的低，python 中默認繼承了操作此款數據庫的引擎 sqlite3 說是引擎不如說就是數據庫的封裝版，開發自用小程序的使用使用它真的大贊

簡單操作SQLite數據庫:創建 sqlite數據庫是一個輕量級的數據庫服務器,該模塊默認集成在python中,開發小應用很不錯.

import sqlite3# 數據表的創建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) # 執行創建表操作

簡單操作SQLite數據庫:簡單的插入語句的使用

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語言’,9,’python’)]insert = 'insert into persion(id,name,age,msg) values(?,?,?,?);'cursor.executemany(insert,data)

簡單的查詢語句的使用

select = 'select * from persion;'cursor.execute(select)#print(cursor.fetchall()) # 取出所有的數據select = 'select * from persion where name=’lyshark’;'cursor.execute(select)print(cursor.fetchall()) # 取出所有的數據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])

簡單的更新數據與刪除

update = 'update persion set name=’蒼老師’ where id=1;'cursor.execute(update)update = 'update persion set name=’蒼老師’ 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()) # 取出所有的數據conn.commit() # 事務提交，每執行一次數據庫更改的操作，就執行提交cursor.close()conn.close()

SQLite小試牛刀 實現用戶名密碼驗證,當用戶輸入錯誤密碼后,自動鎖定該用戶1分鐘.

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:') # 這個地方應該嚴謹驗證,盡量不要讓用戶拼接SQL語句 password = input('passwor:') # 此處為了方便不做任何驗證(注意:永遠不要相信用戶的輸入) 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('當前用戶{}沒有被限制,允許登錄...'.format(username)) if ret[0][0] == username:if ret[0][1] == password: print('用戶 {} 登錄成功...'.format(username))else: print('用戶 {} 密碼輸入有誤..'.format(username)) times = int(time.time()) + 60 cursor.execute('update login set time={} where username=’{}’'.format(times,username)) conn.commit() else:print('用戶名正確,但是密碼錯誤了...') else: print('賬戶 {} 還在限制登陸階段,請等待1分鐘...'.format(username)) else: print('用戶名輸入錯誤')

SQLite檢索時間記錄 通過編寫的TimeIndex函數檢索一個指定范圍時間戳中的數據.

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)# 批量生成一堆數據,用于后期的測試.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 傳入數據庫名稱# table = 指定表lyshark名稱# 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提取數據并繪圖 通過使用matplotlib這個庫函數,并提取出指定時間的數據記錄,然后直接繪制曲線圖.

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文章出處：https://www.cnblogs.com/lyshark

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