[Koha] Report Help

[Nicole Engard]

I am looking at this report in the report library:

SELECT DATE(datetime) AS date, substring(itemcallnumber,1,1) AS 'Call#
range', count(*) AS count FROM statistics LEFT JOIN items USING
(itemnumber) WHERE statistics.type IN ('issue', 'renew') AND
YEAR(datetime) = 2010 GROUP BY DATE(datetime),
substring(itemcallnumber,1,1)

And I'm wondering if anyone knows how I could change that substring
bit to show me everything before the first space.  For example I want
F but I also want JFIC - basically I want to lump it together using
the first bit of the call number - the bit before the space.

Thanks in advance,
Nicole