Checking for empty queryset in Python/MySQLdb

Question

I can't seem to find a simple answer for this question. I am using MySQLdb for Python and I am running a select statement, I want to check if an empty query set is returned.

get_port = db.cursor()
get_port.execute(""" SELECT port FROM nar_ports WHERE port=%s AND hostname=%s;""", (device_port,PE))

I have tried

if not get_port:

This doesn't match. So then I tried

for result in get_port.fetchall():
    existing_port = result[0]
if not existing_port:

But it doesn't even seem to enter the loop. So then I tried to check the length

if len(get_port) == 0:

But it seems you can't run len on a sql object. So I check if the object has a none value.

if get_port = None:

But this doesn't seem to work either.

I'm certain there is a simple solution for this but I cannot seem to find it. Any help would be greatly appreciated. Thanks in advance.

cheers

pydsigner · Accepted Answer · 2013-03-13 00:09:38Z

3

It is simple, though you almost had a longer way.

if get_port.fetchone():
    do_something_here()

You could also have used

if len(get_port.fetchmany()):
    do_something_here()

But that is longer and less efficient.

answered Mar 13, 2013 at 0:09

pydsigner

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3 Comments

dlyxzen Over a year ago

Hey Pydsigner, man I was so close, dam! lol. Thank you for your response, that worked. Thanks so much!

pydsigner Over a year ago

No problem! It's a pleasure to help people who have already done so much to help themselves. BTW, you can accept and/or upvote my answer, which will help other helpful people from coming in to answer your question again.

pydsigner Over a year ago

Thank you and the same to you.

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