Question

我在使用 Python 脚本时遇到问题，无论我给脚本提供什么参数，它都不会执行 if 分支。我的代码有问题吗？我正在执行一个 HTML 表单，结果没问题，直到我向 else 语句添加了一些内容......我已经尝试了一切，但它仍然不想工作......

#!/usr/bin/python3
import pymysql
import cgi
from http import cookies
# Open database connection
db = pymysql.connect("localhost","superadmin","123","dinamic" )

# prepare a cursor object using cursor() method
cursor = db.cursor()
data=cgi.FieldStorage()
a=data.getvalue('e1')
b=data.getvalue('p1')

# Prepare SQL query to fetch a record into the database.
sql = "SELECT id, email, password FROM register WHERE email = %s AND password = %s"
try:
   # Execute the SQL command
   cursor.execute(sql, (a, b))
   # Commit your changes in the database
   db.commit()
   c=cookies.SimpleCookie()
   # assign a value
   c['mou']=a

   # set the xpires time
   c['mou']['expires']=24*60*60

   # print the header, starting with the cookie
   print (c)
   print("Content-type: text/html", end="\r\n\r\n", flush=True);
   print('''<html><head><title>First python script for Security and Encrpytion class</title></head><body><center><h2>Successfully login!</h2><br><img src='image/2.gif'></body></html>''');

except:
   db.commit()
   print("Content-type: text/html", end="\r\n\r\n", flush=True);
   print("<html>");
   print("<body>");
   print("<center>")
   print("<h2>Fail to login!</h2>");
   print("<img src='image/dinamic.gif'>");
   print("</body>");
   print("</html>");
   # Rollback in case there is any error
   db.rollback()

Answer 1

cursor.execute() 不返回选择的行数。您可以调用 cursor.fetchone() 来查看它是否返回一行。

也无需调用 db.commit()，因为您还没有进行任何更改。

try:
    # Execute the SQL command
    cursor.execute(sql, (a, b)))
    row = cursor.fetchone()
    if row:
        c=cookies.SimpleCookie()

        # assign a value
        c['mou']=a

        # set the xpires time
        c['mou']['expires']=24*60*60

        # print the header, starting with the cookie
        print (c);
        print ("Content-type: text/html", end="\r\n\r\n", flush=True);
        print("");
        print('''<html><head><title>Security & Encryption class - First script</title></head><body><h2>successfully login!</h2>''');
        print("<center>");
        print("<img src='image/successfully.gif'>");
        print("</center>");
        print("</body></html>");
    else:
        print ("Content-type: text/html", end="\r\n\r\n", flush=True)
        print("<html>")
        print("<body>")
        print("<center>")
        print("<h2>Login fail!</h2>")
        print("<img src='image/dinamic.gif'>")
        print("<br><br>")
        print('<button id="myButton" class="float-left submit-button" >Home</button>')
        print('''<script type="text/javascript">
         document.getElementById("myButton").onclick = function () {
             location.href = "index.html";
         };
        </script>''');
        print("</center>");
        print("</body>");
        print("</html>");
except:
    # Rollback in case there is any error
    db.rollback()

为什么它是 else 语句被执行，如果它被忽略？

1 个答案: