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Python 操作SQLite數(shù)據(jù)庫詳情

 更新時間：2021年11月11日 17:25:28   作者：lyshark  
這篇文章主要介紹了Python 操作SQLite數(shù)據(jù)庫，SQLite，是一款輕型的數(shù)據(jù)庫，是遵守ACID的關(guān)系型數(shù)據(jù)庫管理系統(tǒng)，它包含在一個相對小的C庫中，下面來看看詳細(xì)內(nèi)容,需要的朋友可以參考一下

前言：

SQLite屬于輕型數(shù)據(jù)庫，遵守ACID的關(guān)系型數(shù)據(jù)庫管理系統(tǒng)，它包含在一個相對小的C庫中。在很多嵌入式產(chǎn)品中使用了它，它占用資源非常的低，python 中默認(rèn)繼承了操作此款數(shù)據(jù)庫的引擎 sqlite3 說是引擎不如說就是數(shù)據(jù)庫的封裝版，開發(fā)自用小程序的使用使用它真的大贊

一、簡單操作SQLite數(shù)據(jù)庫

簡單操作SQLite數(shù)據(jù)庫:創(chuàng)建 sqlite數(shù)據(jù)庫是一個輕量級的數(shù)據(jù)庫服務(wù)器,該模塊默認(rèn)集成在python中,開發(fā)小應(yīng)用很不錯.

import sqlite3

# 數(shù)據(jù)表的創(chuàng)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(zhí)行創(chuàng)建表操作

1、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)

2、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(shù)據(jù)

select = "select * from persion where name='lyshark';"
cursor.execute(select)
print(cursor.fetchall())   # 取出所有的數(shù)據(jù)

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、更新數(shù)據(jù)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(shù)據(jù)

conn.commit()       # 事務(wù)提交，每執(zhí)行一次數(shù)據(jù)庫更改的操作，就執(zhí)行提交
cursor.close()
conn.close()

三、實現(xiàn)用戶名密碼驗證

當(dāng)用戶輸入錯誤密碼后,自動鎖定該用戶1分鐘.

import sqlite3
import re,time

conn = 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(yīng)該嚴(yán)謹(jǐn)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(yuǎn)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(dāng)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")

四、SQLite檢索時間記錄

通過編寫的TimeIndex函數(shù)檢索一個指定范圍時間戳中的數(shù)據(jù).

import os,time,datetime
import 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(shù)據(jù),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(shù)據(jù)庫名稱
# table = 指定表lyshark名稱
# start = 2019-12-12 14:28:00
# ends  = 2019-12-12 14:29:20
def 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提取數(shù)據(jù)并繪圖

通過使用matplotlib這個庫函數(shù),并提取出指定時間的數(shù)據(jù)記錄,然后直接繪制曲線圖.

import os,time,datetime
import sqlite3
import numpy as np
from matplotlib import pyplot as plt

def 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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