Python SQLite Return Value

Question

I am trying to return a numeric value from this statement:

c = db.execute("""SELECT *, rowid FROM members WHERE barcode = '%s' AND debit > 0 LIMIT 50""" % (s,))

But I get this as the returned value:

sqlite3.Cursor object at 0xb6cb2720

What should I do with this cursor object to get the results?

To retrieve data after executing a SELECT statement, you can either treat the cursor as an iterator, call the cursor’s fetchone() method to retrieve a single matching row, or call fetchall() to get a list of the matching rows. — roippi
– roippi, Commented Sep 4, 2014 at 0:27

AstroCB · Accepted Answer · 2014-09-04 01:39:48Z

4

Try this:

for row in c:
    print row['rowid']

edited Sep 4, 2014 at 1:39

AstroCB

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answered Sep 4, 2014 at 0:30

chishaku

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8 Comments

cdhowie Over a year ago

Directly enumerating c instead of c.fetchall() will require less memory since the entire result set isn't loaded into memory all at once, rather each row would be loaded in one at a time and discarded before the next.

chishaku Over a year ago

Updated. Thanks for the tip. This is why I love answering questions on SO. My way of thinking is validated or not and either way, I learn something.

Jon Clements Over a year ago

@cdhowie actually SQLite will not necessarily return the entire result set, but it certainly buffers some in memory before returning the next set from a transactional log on disk (unless it's an in-mem DB)... But yes, still certainly more efficient than list'ing or .fetchall'ing the results.

cdhowie Over a year ago

@JonClements Of course. Buffering is good for performance. But the DB engine knows how much it should buffer to perform better; pulling the entire set into memory is likely to be much worse.

Jon Clements Over a year ago

@cdhowie the slight trade off being that if it's "not that large" - than requesting the whole lot is often more efficient (doesn't require transactional locks and logs for so long) than requesting chunks... but I'm going off-topic here :)

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Issac_n · Accepted Answer · 2020-12-15 14:42:10Z

0

try this>>print(cursorObject.fetchone()[0])

answered Dec 15, 2020 at 14:42

Issac_n

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Comments

VitOk · Accepted Answer · 2021-09-28 12:55:49Z

0

I just convert to list of tuples

sql="SELECT *, rowid FROM members WHERE barcode = '%s' AND debit > 0 LIMIT 50" % (s,)
c = list(db.execute(sql)

answered Sep 28, 2021 at 12:55

VitOk

1

Comments

bad_coder · Accepted Answer · 2021-09-28 13:05:12Z

0

One of my problems was, I was using the wrong SQL query to get the data I wanted. See:

c = db.execute("""SELECT "debit" FROM "members" WHERE "barcode" = '%s' LIMIT 1""" % (s,))

I would then get the response:

(0,)

Which was what I needed. Now to actually work out how to compare it - I need to say "if c is not equal to (0,) then print 'cross' else print 'tick'..."

edited Sep 28, 2021 at 13:05

bad_coder

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answered Sep 4, 2014 at 6:50

Shane Morris

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