Python MySQL Connector database query with %s fails [duplicate]

Question

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Why do I get "TypeError: not all arguments converted during string formatting" when trying to use a string in a parameterized SQL query? (8 answers)

Closed 4 months ago.

I have a basic program that is supposed to query a database that contains user information. I am trying to select the information for a specific user and print it out to the console.

Here is my code:

import mysql.connector

funcon = mysql.connector.connect(user='root', password='pass', host='127.0.0.1', database='fundata')
funcursor = funcon.cursor()

query = ("SELECT * FROM funtable WHERE userName=%s")
uName = 'user1'

funcursor.execute(query, uName)

for (userName) in funcursor:
    print("{}".format(userName))

I have the username stored in a variable because later I plan on getting the user name from a tkinter entry box. When I execute this code I get the following error:

mysql.connector.errors.ProgrammingError: 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '%s' at line 1

I have tried putting the %s in quotes in the query but then it literally searches for a user names '%s' and returns nothing. How can I change my code so I can query the database for only this user?

Thank you.

FYI: I am using python 3.3.

Answer 1

Change your funcursor.execute(query, uName) call to:

funcursor.execute(query, (uName, ))

The second argument in execute takes a list/tuple of strings, not a string. The above call creates the tuple before passing in the string to execute, so no error is thrown.

The reason why execute takes a list/tuple of strings is because it does not know beforehand how many strings it needs in order to satisfy your query.