imploding a list for use in a python MySQLDB IN clause

Question

I know how to map a list to a string:

foostring = ",".join( map(str, list_of_ids) )

And I know that I can use the following to get that string into an IN clause:

cursor.execute("DELETE FROM foo.bar WHERE baz IN ('%s')" % (foostring))

What I need is to accomplish the same thing SAFELY (avoiding SQL injection) using MySQLDB. In the above example because foostring is not passed as an argument to execute, it is vulnerable. I also have to quote and escape outside of the mysql library.

(There is a related SO question, but the answers listed there either do not work for MySQLDB or are vulnerable to SQL injection.)

Answer 1

Use the list_of_ids directly:

format_strings = ','.join(['%s'] * len(list_of_ids))
cursor.execute("DELETE FROM foo.bar WHERE baz IN (%s)" % format_strings,
                tuple(list_of_ids))

That way you avoid having to quote yourself, and avoid all kinds of sql injection.

Note that the data (list_of_ids) is going directly to mysql's driver, as a parameter (not in the query text) so there is no injection. You can leave any chars you want in the string, no need to remove or quote chars.

Answer 2

Did somebody take a look on MySQLdb source code? If not I suggest you to look at it - mainly because MySQLdb create the query on the client side and doesn't pass parameters to the server!

So it doesn't matter how you use it your code is vulnerable!