And now that I've actually tried that query, there are problems with it. Here is a fixed version: SELECT YEAR(issuedate), MONTH(issuedate), categorycode, COUNT(DISTINCT borrowernumber) FROM ( SELECT issuedate, borrowernumber FROM old_issues UNION ALL SELECT issuedate, borrowernumber FROM issues ) AS all_issues LEFT JOIN borrowers USING (borrowernumber) GROUP BY YEAR(issuedate), MONTH(issuedate), categorycode On Mon, Jan 9, 2012 at 1:31 PM, Galen Charlton <gmc@esilibrary.com> wrote:
Hi,
On 01/09/2012 03:30 PM, Mike Hafen wrote:
I've seen UNION used to join those two tables in queries. I'm imaginning something like:
SELECT YEAR(issuedate), MONTH(issuedate), categorycode, COUNT(DISTINCT borrowernumber) FROM ( SELECT issuedate,categorycode,**borrowernumber FROM old_issues UNION ALL SELECT issuedate,categorycode,**borrowernumber FROM issues ) LEFT JOIN borrowers USING (borrowernumber) GROUP BY YEAR(issuedate), MONTH(issuedate), categorycode;
A UNION ALL is indeed a valid way to do it.
Regards,
Galen -- Galen Charlton Director of Support and Implementation Equinox Software, Inc. / The Open Source Experts email: gmc@esilibrary.com direct: +1 770-709-5581 cell: +1 404-984-4366 skype: gmcharlt web: http://www.esilibrary.com/ Supporting Koha and Evergreen: http://koha-community.org & http://evergreen-ils.org
______________________________**_________________ Koha-devel mailing list Koha-devel@lists.koha-**community.org<Koha-devel@lists.koha-community.org> http://lists.koha-community.**org/cgi-bin/mailman/listinfo/**koha-devel<http://lists.koha-community.org/cgi-bin/mailman/listinfo/koha-devel> website : http://www.koha-community.org/ git : http://git.koha-community.org/ bugs : http://bugs.koha-community.**org/ <http://bugs.koha-community.org/>