Python 2.4 vs 2.5 - Unicode error

John Machin sjmachin at
Thu Jan 22 01:08:54 CET 2009

On Jan 22, 9:50 am, Gaurav Veda <vedagau... at> wrote:
> > The 0xc2 strongly suggests that you are feeding the beast data encoded
> > in UTF-8 while giving it no reason to believe that it is in fact not
> > encoded in ASCII. Curiously the first errant byte is a long way (4KB)
> > into your data. Consider doing
> >     print repr(data)
> > to see what you've actually got there.
> >>> sqlStr[4352:4362]
> ' and 25\xc2\xb0F'

That's the UTF-8 version of ' and 25°F' where the character between
the 25 and the F is U+00B0 DEGREE SIGN ... interesting stuff to have
in an SQL query string.

> All I want to do is to just replace all the non-ascii characters by a
> space.

I can't imagine why you would want to do that to data, let alone to an
SQL query.

I can't see any evidence that you actually tried to do that, anyway.

To replace non-ASCII characters in a UTF-8-encoded string by spaces:
| >>> u8 = ' and 25\xc2\xb0F'
| >>> u = u8.decode('utf8')
| >>> ''.join([chr(ord(c)) if c <= u'\x7f' else ' ' for c in u])
| ' and 25 F'

> > I'm a little skeptical about the "2.4 works, 2.5 doesn't" notion --
> > different versions of mysql, perhaps?
> I am trying to put content into the mysql server running on machine A,
> from machine B & machine C with different versions of python. So I
> don't think this is a mysql issue.

Terminology confusion. Consider the possibility of different versions
of MySQLdb (the client interface package) on the client machines B and

Also consider the possibility that you didn't run exactly the same
code on B and C.

> > Show at the very least the full traceback that you get. Try to write a
> > short script that demonstrates the problem with 2.5 and no problem
> > with 2.4, so that (a) it is apparent what you are doing (b) the
> > problem can be reproduced if necessary by someone with access to
> > mysql.

How about a very small script which includes the minimum necessary to
run these two lines (with appropriate substitutions for column_x and
sql_str = "select column_x from table_y where column_x = '\xc2\xb0'"

and run that on B and C

> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
>   File "", line 164, in <module>
>     cursor.execute(sqlStr)
>   File "/usr/lib64/python2.5/site-packages/MySQLdb/", line
> 146, in execute
>     query = query.encode(charset)
> UnicodeDecodeError: 'ascii' codec can't decode byte 0xc2 in position
> 4359: ordinal not in range(128)
> > You might like to explain why you think that doubling backslashes in
> > your SQL is a good idea, and amplify "some processing on the text".
> I thought this will achieve 2 things.
> a) It will escape any unicode character (obviously, I was wrong. Got
> carried away by the display. I thought \xc2 will get escaped to \\xc2,
> which is completely preposterous).
> b) It will make sure that the escape sequences in the string (e.g.
> '\n') are received by mysql as an escape sequence.

Run-time programmatic fiddling with an SQL query string is dangerous
and tricky at the best of times, worse when you don't inspect the
result before you press the launch button.


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