What's wrong with my code?

[A Former User]

@VRonin i try to remove the if(self.query.exec_()) and modify with .next() but still not showing my print statement account doesn't exist

[VRonin]

no, you don't have to modify anything.

 if(!self.query.exec()):
            print "Database query failed"
            return False

checks that the database ran the query correctly, it says nothing on the data inside it. the next block

 if(self.query.next()):
                if USERNAME == "admin":
                    print "Login as Administrator"
                else:
                    print "Log is as User"
                return True

here we check if the username and passwords were in the database

[A Former User]

@VRonin i understand now Thank you very much! i remove the "not" function and it works

[A Former User]

@Gelo but the problem is everytime i input a correct query for example the admin account it prints the "login as admin" and but after it print the admin mode "Database query failed" shows up first

[VRonin]

could you post your current code?

[A Former User]

@VRonin

def Submit_btn(self):
    USERNAME = self.username.text()
    PASSWORD = self.password.text()
    
    self.query = QSqlQuery()
    self.query.prepare("SELECT username FROM users WHERE username = '%s' and password = '%s'"%(USERNAME,str(PASSWORD)))
    self.query.addBindValue(USERNAME)    
    self.query.addBindValue(PASSWORD)
    
    if(self.query.exec_()):
        print "Database query failed"
        self.ctr += 1
        print self.ctr
    if self.ctr >= 3:
        print "3 wrong attemps will terminate in a second!"
        time.sleep(2)
        sys.exit()
        return False
    if(self.query.next()):
            if USERNAME == "admin":
                print "Login as Administrator"
                print self.query.exec_()
                subprocess.Popen("__init__.py",shell=True)
                sys.exit()
            else:
                print "View Mode!"
                sys.exit()
            return True

[VRonin]

@Gelo said in Whats wrong with my code!:

self.query.prepare("SELECT username FROM users WHERE username = '%s' and password = '%s'"%(USERNAME,str(PASSWORD)))

http://www.w3schools.com/sql/sql_injection.asp

if(self.query.exec_()):

why did you remove the not? it should be if(not self.query.exec_()):

print "3 wrong attemps will terminate in a second!"

you are not checking the attempts in the in the right place

print self.query.exec_()

why are you executing the query again?

if(not self.query.exec_()):
	print "Database query failed"
else:
	if(self.query.next()):
		if USERNAME == "admin":
			print "Login as Administrator"
			print self.query.exec_()
			subprocess.Popen("__init__.py",shell=True)
			sys.exit()
		else:
			print "View Mode!"
			sys.exit()
		return True
	else:
		self.ctr += 1
		print self.ctr
		if self.ctr >= 3:
			print "3 wrong attemps will terminate in a second!"
			time.sleep(2)
			sys.exit()
		return False

[A Former User]

@VRonin i remove the not function because it does not print the message if i enter wrong inputs

[VRonin]

if(not self.query.exec()): checks that the query did run correctly, it does not check your input.
The input is checked by if(self.query.next()): if that is true then username and password were found in the database.

Please do not overlook the SQL injection bug:

self.query.prepare("SELECT username FROM users WHERE username = '%s' and password = '%s'"%(USERNAME,str(PASSWORD)))
http://www.w3schools.com/sql/sql_injection.asp

[the_]

@Gelo said in Whats wrong with my code!:

    self.query = QSqlQuery()
    self.query.prepare("SELECT username FROM users WHERE username = '%s' and password = '%s'"%(USERNAME,str(PASSWORD)))
    self.query.addBindValue(USERNAME)    
    self.query.addBindValue(PASSWORD)

I just wonder this works... did you read http://pyqt.sourceforge.net/Docs/PyQt4/qsqlquery.html for how to use prepare statement and binding values?

To bind values to a prepared statement you need placeholders.
According to the examples on http://pyqt.sourceforge.net/Docs/PyQt4/qsqlquery.html it should be done like this:

Named binding using named placeholders:

 QSqlQuery query;
 query.prepare("INSERT INTO person (id, forename, surname) "
               "VALUES (:id, :forename, :surname)");
 query.bindValue(":id", 1001);
 query.bindValue(":forename", "Bart");
 query.bindValue(":surname", "Simpson");
 query.exec();

Positional binding using named placeholders:

 QSqlQuery query;
 query.prepare("INSERT INTO person (id, forename, surname) "
               "VALUES (:id, :forename, :surname)");
 query.bindValue(0, 1001);
 query.bindValue(1, "Bart");
 query.bindValue(2, "Simpson");
 query.exec();

Binding values using positional placeholders (version 1):

 QSqlQuery query;
 query.prepare("INSERT INTO person (id, forename, surname) "
               "VALUES (?, ?, ?)");
 query.bindValue(0, 1001);
 query.bindValue(1, "Bart");
 query.bindValue(2, "Simpson");
 query.exec();

Binding values using positional placeholders (version 2):

 QSqlQuery query;
 query.prepare("INSERT INTO person (id, forename, surname) "
               "VALUES (?, ?, ?)");
 query.addBindValue(1001);
 query.addBindValue("Bart");
 query.addBindValue("Simpson");
 query.exec();