SQLite数据库

Posted 2021-12-11 gyy-15768200938

SQLite3 of python

一、SQLite3 数据库

　　SQLite3 可使用 sqlite3 模块与 Python 进行集成，一般 python 2.5 以上版本默认自带了sqlite3模块，因此不需要用户另外下载。

描述

　　Python的数据库模块有统一的接口标准，所以数据库操作都有统一的模式（假设数据库模块名为db）：

　　1. 用db.connect创建数据库连接，假设连接对象为conn

　　2. 如果该数据库操作不需要返回结果，就直接使用conn.execute查询，根据数据库事物隔离级别的不同，可能修改数据库需要conn.commit

　　3. 如果需要返回查询结果则用conn.cursor创建游标对象cur,通过cur.execute查询数据库，cursor方法有fetchall、fetchone、fetchmany返回查询结果，根据数据库事物隔离级别不同，可能修改数据库需要coon.commit

　　4. 关闭cur.close

基本操作实例如下：

#coding=utf-8

import sqlite3

conn = sqlite3.connect("sqlite.db")  #创建sqlite.db数据库
print ("open database success")
conn.execute("drop table IF EXISTS student")
query = """create table IF NOT EXISTS student(
    customer VARCHAR(20),
    produce VARCHAR(40),
    amount FLOAT,
    date DATE   
);"""
conn.execute(query)
print ("Table created successfully")

#在表中插入数据

‘‘‘ 方法1 ‘‘‘
#data = ‘‘‘INSERT INTO student(customer,produce,amount,date)\\
#    VALUES("zhangsan","notepad",999,"2017-01-02")‘‘‘
#conn.execute(data)
#data = ‘‘‘INSERT INTO student(customer,produce,amount,date)\\
#    VALUES("lishi","binder",3.45,"2017-04-05")‘‘‘
#conn.execute(data)
#conn.commit()

‘‘‘ 方法2 ‘‘‘
statement = "INSERT INTO student VALUES(?,?,?,?)"
data = [("zhangsan","notepad",999,"2017-01-02"),("lishi","binder",3.45,"2017-04-05")]
conn.executemany(statement, data)
conn.commit()

curson = conn.execute("select * from student")
conn.commit()
print (curson)
rows = curson.fetchall()
print (rows)
conn.close()

Python爬取大学排名，直接上代码吧

# -*- coding: utf-8 -*-
"""
Created on Wed May 29 22:44:12 2019

@author: guo‘yu‘yi
"""

import sqlite3
from pandas import DataFrame
import re
class SQL_method:
    def __init__(self, dbName, tableName, data, columns, COLUMNS, Read_All=True):
        self.dbName = dbName
        self.tableName = tableName
        self.data = data
        self.columns = columns
        self.COLUMNS = COLUMNS
        self.Read_All = Read_All
    def creatTable(self):
        connect = sqlite3.connect(self.dbName)
        connect.execute("CREATE TABLE {}({})".format(self.tableName, self.columns))
        connect.commit()
        connect.close()
    def insertDataS(self):
        connect = sqlite3.connect(self.dbName)
        connect.executemany("INSERT INTO {} VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?)".format(self.tableName), self.data)
        connect.commit()
        connect.close()
    def searchData(self, conditions, IfPrint=True):
        connect = sqlite3.connect(self.dbName)
        cursor = connect.cursor()
        cursor.execute("SELECT * FROM {} WHERE {}".format(self.tableName, conditions))
        data = cursor.fetchall()
        cursor.close()
        connect.close()
        if IfPrint:
            self.printData(data)
        return data
    def printData(self, data):
        print("{1:{0}^3}{2:{0}<11}{3:{0}<4}{4:{0}<4}{5:{0}<5}{6:{0}<5}{7:{0}^5}{8:{0}^5}{9:{0}^5}{10:{0}^5}{11:{0}^5}{12:{0}^6}{13:{0}^5}".format(chr(12288), *self.COLUMNS))
        for i in range(len(data)):
            print("{1:{0}<4.0f}{2:{0}<10}{3:{0}<5}{4:{0}<6}{5:{0}<7}{6:{0}<8}{7:{0}<7.0f}{8:{0}<8}{9:{0}<7.0f}{10:{0}<6.0f}{11:{0}<9.0f}{12:{0}<6.0f}{13:{0}<6.0f}".format(chr(12288), *data[i]))
    def getAllData(self):
        connect = sqlite3.connect(self.dbName)
        cursor = connect.cursor()
        cursor.execute("SELECT * FROM {}".format(self.tableName))
        dataList = cursor.fetchall()
        connect.close()
        return dataList
    def run(self):
        try:
            self.creatTable()
            print(">>> 数据库创建成功！")
            self.insertDataS()
            print(">>> 表创建、数据插入成功！")
        except:
            print(">>> 数据库已创建！")
        if self.Read_All:
            self.printData(self.getAllData())
    def deleteData(self, conditions):
        connect = sqlite3.connect(self.dbName)
        connect.execute("DELETE FROM {} WHERE {}".format(self.tableName, conditions))
        connect.commit()
        connect.close()
    def destroyTable(self):
        connect = sqlite3.connect(self.dbName)
        connect.execute("DROP TABLE {}".format(self.tableName))
        connect.commit()
        connect.close()
def get_data(fileName):
    data = []
    f = open(fileName, ‘r‘, encoding=‘utf-8‘)
    for line in f.readlines():
        line = line.replace(‘\\n‘, ‘‘)
        line = line.replace(‘%‘,‘‘)
        line = line.split(‘,‘)
        for i in range(len(line)):
            try:
                if line[i] == ‘‘:
                    line[i] = ‘0‘
                line[i] = eval(line[i])
            except:
                continue
        data.append(tuple(line))
    EN_columns = "Rank real, University text, Province text, Grade real, SourseQuality real, TrainingResult real, ResearchScale real,     ReserchQuality real, TopResult real, TopTalent real, TechnologyService real, Cooperation real, TransformationResults real"
    CH_columns =  ["排名", "学校名称", "省市", "总分", "生涯质量", "培养结果(%)", "科研规模", "科研质量", "顶尖成果", "顶尖人才", "科技服务", "产学研合作", "成果转化"]
    return data[1:], EN_columns, CH_columns
if __name__ == "__main__":
    fileName = "D:\\\\python文件\\\\daxuepaimingRank.csv"
    data, EN_columns, CH_columns = get_data(fileName)
    dbName = "db24.db"
    tableName = "university"
    SQL = SQL_method(dbName, tableName, data, EN_columns, CH_columns, False)
    SQL.run()
    print("\\n查找数据项（University = ‘汕头大学‘） :")
    SQL.searchData("University = ‘汕头大学‘", True)
    print("\\n按照科研规模排序（Province = ‘广东省‘） :")
    SQL.searchData("Province = ‘广东省‘ ORDER BY ResearchScale", True)
    Weight = [0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.40, 0.45, 0.5]
    value, sum = [], 0
    sample = SQL.searchData("Province = ‘广东省‘", False)
    for i in range(len(sample)):
        for j in range(len(Weight)):
            sum += sample[i][4+j] * Weight[j]
        value.append(sum)
        sum=0
    university = [university[1] for university in sample]
    uv, tmp = [], []
    for i in range(len(university)):
        tmp.append(university[i])
        tmp.append(value[i])
        uv.append(tmp)
        tmp = []
    df = DataFrame(uv, columns=list(("大学", "总分")))
    df = df.sort_values(‘总分‘)
    df.index = [i for i in range(1, len(uv)+1)]
    print("\\n通过权值运算后重排名的结果：\\n", df)
    SQL.deleteData("Province = ‘北京市‘")
    SQL.deleteData("Province = ‘山东省‘")
    SQL.deleteData("Province = ‘河南省‘")
    SQL.deleteData("Province = ‘山西省‘")
    SQL.deleteData("Province = ‘广东省‘")
    SQL.deleteData("Province = ‘江西省‘")
    print("\\n数据删除成功")
    SQL.printData(SQL.getAllData())
    SQL.destroyTable()
    print("\\n删除成功")

结果如下