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Here is the scenario. In your function you're executing statements using a cursor, but one of them fails and an exception is thrown. Your program exits out of the function before closing the cursor it was working with. Will the cursor float around taking up space? Do I have to close the cursor?
Additionally, the Python documentation has an example of cursor use and says: "We can also close the cursor if we are done with it." The keyword being "can," not "must." What do they mean precisely by this?
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If you leave it open, it stays open until it goes out of scope and garbage collected. At that point it might be safely closed (and I believe sqlite3 does that). But better to be safe than sorry. Close your connections when you will no longer use them.
The sqlite3. Cursor class is an instance using which you can invoke methods that execute SQLite statements, fetch data from the result sets of the queries. You can create Cursor object using the cursor() method of the Connection object/class.
close() Method. Use close() when you are done using a cursor. This method closes the cursor, resets all results, and ensures that the cursor object has no reference to its original connection object.
Cursor objects allow you to keep track of which result set is which, since it's possible to run multiple queries before you're done fetching the results of the first. Also worth keeping in mind: PEP 249 does not define execute on a connection object, this is an sqlite3 extension.
It's probably a good idea (although it might not matter much with sqlite, don't know there, but it'll make your code more portable). Further, with recent Python (2.5+), it's easy:
from __future__ import with_statement from contextlib import closing with closing(db.cursor()) as cursor: # do some stuff You're not obliged to call close() on the cursor; it can be garbage collected like any other object.
But even if waiting for garbage collection sounds OK, I think it would be good style still to ensure that a resource such as a database cursor gets closed whether or not there is an exception.
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