SQLite3 and lastrowid
ian.g.kelly at gmail.com
Tue Nov 16 22:52:42 CET 2010
On Nov 16, 2:08 pm, fuglyducky <fuglydu... at gmail.com> wrote:
> db_connect = sqlite3.connect('test.db')
> cursor = db_connect.cursor()
At this point you haven't executed a query yet, so there is no
meaningful value that cursor.lastrowid can take.
> # Choose random index from DB - need to understand lastrowid
> #row_count = cursor.lastrowid
> #random_row = random.randrange(0, row_count)
This is wrong. The lastrowid is not the number of rows in the table.
It's the row-id of the row that was inserted (if any) by the last
query executed by the cursor. In the case of sqlite3, I think the row-
id is just the primary key if it's an integer (but in general the row-
id is database-dependent), so you *might* be able to get away with it
if you always let it autoincrement when inserting, never delete any
rows, and never change their primary keys. But it's unreliable and
only available immediately after an insert, so don't do it that way.
The proper way to get the number of rows is to use the COUNT aggregate
function, e.g., "SELECT COUNT(*) FROM TABLE1", which will return a
single row with a single column containing the number of rows in
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