Python 操作SQLite數據庫詳情

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前言：

SQLite屬於輕型數據庫，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瞭它，它占用資源非常的低，python 中默認繼承瞭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

一、簡單操作SQLite數據庫

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

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])

二、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()

三、實現用戶名密碼驗證

當用戶輸入錯誤密碼後,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:")  # 這個地方應該嚴謹驗證,盡量不要讓用戶拼接SQL語句
    password = input("passwor:")   # 此處為瞭方便不做任何驗證(註意: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,但是密碼錯誤瞭...")
        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函數檢索一個指定范圍時間戳中的數據.

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)
# 批量生成一堆數據,用於後期的測試.
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 14:29:20
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提取數據並繪圖

通過使用matplotlib這個庫函數,並提取出指定時間的數據記錄,然後直接繪制曲線圖.

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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