爬取最後一步，總是報錯，自己很崩潰，也找不到問題所在，問小組成員也沒人知道

最後請教老師才知道是多建立一個遊標

錯誤程式碼

from bs4 import BeautifulSoup
import requests
import time
import pymysql
class DB:
    def __init__(self,host='',port=3306,user='',password='',db='',charset='utf8'):
        self.conn=pymysql.connect(host=host,user=user,port=port,password=password,database=db,charset=charset)
        self.cur
 
=self.conn.cursor()

    def __enter__(self):
        return self.cur

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.conn.commit()
        self.cur.close()
        self.conn.close()

def dataUrl(url):
    # url='http://www.d3zww.com/book/5/5663/'
    header = {'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.67 Safari/537.36 Edg/87.0.664.52
 
'}
    html = requests.get(url, headers=header)
    html.raise_for_status()
    html.encoding= html.apparent_encoding
    bs = BeautifulSoup(html.text, 'html.parser')
    return bs

def dataHtml(bs, db):
    xname=bs.find('div',{'class':'book_info'}).find('h1').string
    zt=bs.find('div',{'class':"
 
book_list"}).find_all('li')#小說名
    # print(xname)
    # time.sleep(3)
    for i in zt:
        zname = i.find('a').get_text().strip()#章節名稱
        link=i.find('a')['href']#章節連結
        #print(zhangjiename,zhangjielink)
        urll='http://www.d3zww.com/'
        fullUrl=urll+link   # 'http://www.d3zww.com/'+抓取出的章節連結
        link=fullUrl
        print(xname,zname,link)
        # print(fullUrl) # 完整的網頁
        para = [xname,zname,link]
        db.execute('insert into zhangjie(xname,zname,link) values(%s,%s,%s)', para)


def main(db):
    db.execute('select link from xiaoshuo ')  # 查詢欄位
    result = DB.fetchall()  # 獲取所有資料
    # print(result)
    for s in (result):
        #     url = (''.format#(result)
        x = '-'.join(s)
        print(x)

        url = x.format(s)
        bs = dataUrl(url)
        dataHtml(bs,db)
        time.sleep(2)

if __name__ == '__main__':
    with DB(host='localhost',user='root',password='root',db='shixun') as db:
        db.execute('SET NAMES utf8')
        main(db)

正確程式碼

from bs4 import BeautifulSoup
import requests
import time
import pymysql
class DB:
    def __init__(self,host='',port=3305,user='',password='',db='',charset='utf8'):
        self.conn=pymysql.connect(host=host,user=user,port=port,password=password,database=db,charset=charset)
        self.cur=self.conn.cursor()

    def __enter__(self):
        return self.cur

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.conn.commit()
        self.cur.close()
        self.conn.close()

def dataUrl(url):
    # url='http://www.d3zww.com/book/5/5663/'
    header = {'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.67 Safari/537.36 Edg/87.0.664.55'}
    html = requests.get(url, headers=header)
    html.raise_for_status()
    html.encoding= html.apparent_encoding
    bs = BeautifulSoup(html.text, 'html.parser')
    return bs

def dataHtml(bs, db):
    xname=bs.find('div',{'class':'book_info'}).find('h1').string
    zt=bs.find('div',{'class':"book_list"}).find_all('li')#小說名
    # print(xname)
    time.sleep(3)
    for i in zt:
        zhangjiename = i.find('a').get_text().strip()#章節名稱
        zhangjielink=i.find('a')['href']#章節連結
        #print(zhangjiename,zhangjielink)
        urll='http://www.d3zww.com/'
        fullUrl=urll+zhangjielink   # 'http://www.d3zww.com/'+抓取出的章節連結
        print(xname,zhangjiename,fullUrl)
        # print(fullUrl) # 完整的網頁
        para = [xname,zhangjiename, zhangjielink]
        db.execute('insert into zhangjie(xname,zname,link) values(%s,%s,%s)', para)

def main(db):
    for i in range(3731,3741):
        url = "http://www.d3zww.com/book/3/{}/".format(i)
        bs = dataUrl(url)
        dataHtml(bs,db)
        time.sleep(2)

if __name__ == '__main__':
    with DB(host='localhost',user='root',password='root',db='shixun') as db:
        db.execute('SET NAMES utf8')
        main(db)

兩者相比較就會發現兩個程式碼沒多大區別，第二個程式碼比第一個少兩行程式碼，也就是以下兩行

多一個遊標就會出現錯誤，

就好比一個人結婚一樣，第一個已經領了結婚證，第二個再去肯定不會讓辦的。

解釋一下什麼是遊標

遊標（cursor）：系統為使用者開通的一個數據緩衝區，用於存放SQL語句執行結果。使用者使用的sql會逐一的在遊標中獲取記錄，並賦值給主變數，交由Python進一步處理，一組主變數只能存放一條記錄。

告誡一下網路小蜘蛛打程式碼一定要認真，注意事項太多啦，爬蟲真是博大精深!