Erratum:
please read 'if y is *not* None:'. (think that if y = 0, you won't
execute the proper code block with 'if y:').
JM
Jean-Michel Pichavant wrote:
I fall into the same issue when using postgres. Your main concern is
that NULL = NULL will return False. Could seems strange but it has
much advantages sometimes, however this is not the purpose.
I found your solution quite acceptable. Just replace 'if y:' by 'if y
is None:', add a comment to point that #NULL <> NULL to help any
reader that is not familiar with db and you got a perfectly readable
code.
Of course if you have more complex queries to build you'll have to
think about an elegant way to manage NULL values. I personally iterate
trough all my COLs and add a 'COL# = ?' if the value queried is not
None. It works, it's readable, it's simple, it's python :o)
JM
Mitchell L Model wrote:
Suppose I have a simple query in sqlite3 in a function:
def lookupxy(x, y):
conn.execute("SELECT * FROM table WHERE COL1 = ? AND COL2 = ?",
(x, y))
However, COL2 might be NULL. I can't figure out a value for y that
would retrieve rows for which COL2 is NULL. It seems to me that I
have to perform an awkward test to determine whether to execute a
query with one question mark or two.
def lookupxy(x, y):
if y:
conn.execute("SELECT * FROM table WHERE COL1 = ? AND COL2
= ?",
(x, y))
else:
conn.execute("SELECT * FROM table WHERE COL1 = ? AND COL2
IS NULL",
(x,))
The more question marks involved the more complicated this would get,
especially if question marks in the middle of several would sometimes
need to be NULL. I hope I'm missing something and that someone can
tell me what it is.
--
http://mail.python.org/mailman/listinfo/python-list
