My Python code error with mysql select please help me

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#=========login================
def loginCheck(self):
    Username = self.txt_name.text()
    Password = self.txt_Password.text()

    mydb = mysql.connector.connect( host="localhost",  user="root",  passwd="",  database ="mydatabase")
    mydb = mydb.cursor()
    mydb.execute("select * from tbl_name where name ='"Username"' && password = '"Password"'")

    if(len(myresult = mydb.fetchone()) > 0):
        print("user found !")
    else:
        print("User Not found !")

What I have tried:

<pre>  File "d:\from\fromlogin.py", line 20
    mydb.execute("select * from tbl_name where name = '"Username"' && password = '"Password"';")
                                                               ^
SyntaxError: invalid syntax

the message it
i try but it still so error like this

Posted 10-Jun-19 23:53pm

Member 11271238

Updated 11-Jun-19 0:22am

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Richard MacCutchan · Accepted Answer · 2019-06-11T00:07:00

You need to use the + sign to concatenate literal strings with variable values:

Python

mydb.execute("select * from tbl_name where name = '" + Username + "' && password = '" + Password + "';")

However, you should never store passwords in clear text, it leaves your system vulnerable to hackers. Use a hash method to convert the password into a salted hash (Google it) for a more secure system.

OriginalGriff · Accepted Answer · 2019-06-11T00:22:00

In addition to what Richard has said, Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Always use Parameterized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'

The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'

Which SQL sees as three separate commands:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';

A perfectly valid SELECT

SQL

DROP TABLE MyTable;

A perfectly valid "delete the table" command

SQL

--'

And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

And with your current code, I can bypass yo password checking completely by adding "'--" to the end of any username ...

See here for some info on how to hash passwords: Password Storage: How to do it.[^]

And remember: if this is web based and you have any European Union users then GDPR applies and that means you need to handle passwords as sensitive data and stored them in a safe and secure manner. Text is neither of those and the fines can be .... um ... outstanding. In December 2018 a German company received a relatively low fine of €20,000 for just that.

My Python code error with mysql select please help me

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