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Jane> I browsed through the archives of this site, but I didn't see how
Jane> to check if a SELECT through the MySql module returns an empty set
Jane> (whether a row exists or not, the "else" part below is always
Jane> called).

The return value of the cursor's execute method indicates how many rows were
selected:

>>> import MySQLdb
>>> conn = MySQLdb.Connection(...)
>>> curs = conn.cursor()
>>> print curs.execute("select * from cities where city like 'San %'")
51
>>> rows = curs.fetchall()
>>> print len(rows)
51

Skip

"Skip Montanaro" <> wrote in message
news:mailman.1059075503.7037.python-...
>
> Jane> I browsed through the archives of this site, but I didn't see
how
> Jane> to check if a SELECT through the MySql module returns an empty
set
> Jane> (whether a row exists or not, the "else" part below is always
> Jane> called).
>
> The return value of the cursor's execute method indicates how many rows
were
> selected:
>
> >>> import MySQLdb
> >>> conn = MySQLdb.Connection(...)
> >>> curs = conn.cursor()
> >>> print curs.execute("select * from cities where city like 'San %'")
> 51
> >>> rows = curs.fetchall()
> >>> print len(rows)
> 51
>

Alternatively, you can observer that the fetchall() method will return an
empty list, and use

if not rows:
# empty set returned

This is a bit more portable, which is maybe not important, but if you
planned to distribute your software to users with other database platforms,
not all DBI modules' execute() methods return the row count.

regards
--
Steve Holden http://www.holdenweb.com/
Python Web Programming http://pydish.holdenweb.com/pwp/

On Thu, 24 Jul 2003 21:05:13 GMT, "Steve Holden"
<> wrote:
>Alternatively, you can observer that the fetchall() method will return an
>empty list, and use
>
> if not rows:
> # empty set returned

Thx to you both. That did it

JD.