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Python 操作SQLite數(shù)據(jù)庫的示例

 更新時間：2020年10月16日 15:48:07   作者：lyshark  
這篇文章主要介紹了Python 操作SQLite數(shù)據(jù)庫的示例，幫助大家更好的利用python操作數(shù)據(jù)庫處理數(shù)據(jù)，感興趣的朋友可以了解下

SQLite，是一款輕型的數(shù)據(jù)庫，是遵守ACID的關系型數(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

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)庫服務器,該模塊默認集成在python中,開發(fā)小應用很不錯.

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

簡單操作SQLite數(shù)據(jù)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(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])

簡單的更新數(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()

SQLite小試牛刀 實現(xiàn)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 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(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")

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()

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

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