mysql 5.6: group_concat help sought - mysql

Question

I have the tables:
CREATE TABLE IF NOT EXISTS `buildingAccess` (
`id` int(10) unsigned NOT NULL,
`building` varchar(16) NOT NULL,
`person` varchar(16) NOT NULL,
`enteryDate` datetime NOT NULL,
`exitDate` datetime DEFAULT NULL
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8;
INSERT INTO `buildingAccess` (`id`, `building`, `person`, `enteryDate`, `exitDate`) VALUES
(1, 'Lot B-3', 'Alice Jones', '2015-11-10 05:29:14', '2015-11-10 15:18:42'),
(3, 'Lot B-3', 'Alice Jones', '2015-11-11 07:11:27', '2015-11-11 12:43:34'),
(7, 'Lot B-3', 'Alice Jones', '2015-12-10 07:11:27', '2015-12-11 12:43:34'),
(2, 'Lot B-3', 'Bill Mayhew', '2015-11-10 10:29:14', '2015-11-10 12:18:42'),
(4, 'Lot B-3', 'Bill Mayhew', '2015-11-12 09:10:27', '2015-11-13 02:43:34'),
(8, 'Lot B-3', 'Bill Mayhew', '2015-11-12 09:10:27', '2015-11-13 02:43:34'),
(5, 'Lot B-3', 'Charlotte Ahn', '2015-12-01 05:29:14', NULL),
(6, 'Lot B-3', 'Dennis Lowe', '2015-12-10 10:29:14', '2015-12-10 12:18:42');
CREATE TABLE IF NOT EXISTS `buildingNotes` (
`building` varchar(16) NOT NULL,
`observer` varchar(16) NOT NULL,
`observationDate` datetime NOT NULL,
`note` varchar(64) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `buildingNotes` (`building`, `observer`, `observationDate`, `note`) VALUES
('Lot B-3', 'Alice Jones', '2015-11-10 05:32:12', 'burned out light on pole South-22'),
('Lot B-3', 'Alice Jones', '2015-11-10 05:39:12', 'burned out light on pole West-7'),
('Lot B-3', 'Alice Jones', '2015-11-10 05:42:12', 'overfull trash can near pole North-11'),
('Lot B-3', 'Charlotte Ahn', '2015-12-01 06:09:14', 'change drawr running low at gate 3');
ALTER TABLE `buildingAccess`
ADD PRIMARY KEY (`id`), ADD KEY `building` (`building`,`person`,`enteryDate`,`exitDate`);
ALTER TABLE `buildingNotes`
ADD KEY `building` (`building`,`observer`,`observationDate`,`note`);
ALTER TABLE `buildingAccess`
MODIFY `id` int(10) unsigned NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=9;
My goal is a query that returns a list of all records in the buildingAccess table. Each should have a notes field that is the GROUP_CONCAT of all of the buildingNotes.note entries made during that record's dates/times bracketed by buildingAccess.enteryDate and buildingAccess.exitDate.
I have tried a few things but am stuck at:
select
BA.building,
BA.person,
BA.enteryDate,
IFNULL(BA.exitDate, NOW()),
IFNULL(
GROUP_CONCAT(
'<p>',
BN.observationDate, ': ',
BN.observer, ': ', BN.note,
'</p>'
ORDER BY BN.observationDate ASC
SEPARATOR ''
),
''
)
from
buildingAccess BA
LEFT JOIN buildingNotes BN ON
BN.building = BA.building
AND BN.observationDate BETWEEN BA.enteryDate AND BA.exitDate
group by BN.building
This returns:
+----------+---------------+---------------------+---------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| building | person | enteryDate | exitDate | observations |
+----------+---------------+---------------------+---------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Lot B-3 | Charlotte Ahn | 2015-12-01 05:29:14 | 2016-01-23 23:04:04 | |
| Lot B-3 | Alice Jones | 2015-11-10 05:29:14 | 2015-11-10 15:18:42 | <p>2015-11-10 05:32:12: Alice Jones: burned out light on pole South-22</p><p>2015-11-10 05:39:12: Alice Jones: burned out light on pole West-7</p><p>2015-11-10 05:42:12: Alice Jones: overfull trash can near pole North-11</p> |
+----------+---------------+---------------------+---------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
I expected to see all of the other buildingAccess records even if there were no buildingNotes records.
I am assuming that I am not "grouping by" the right things but i have not found the right combination yet.
Pointers?

Answer 1

I believe it is due to use BN.building which is from the outer joined table in the GROUP BY clause. Try the following:
SELECT
BA.building
, BA.person
, BA.enteryDate
, IFNULL(BA.exitDate, NOW())
, IFNULL (
GROUP_CONCAT (
'<p>',
BN.observationDate, ': ',
BN.observer, ': ', BN.note,
'</p>'
ORDER BY BN.observationDate ASC
SEPARATOR ''
)
,''
)
FROM buildingAccess BA
LEFT JOIN buildingNotes BN ON BN.building = BA.building
AND BN.observationDate BETWEEN BA.enteryDate AND BA.exitDate
GROUP BY
BA.building
, BA.person
, BA.enteryDate
, IFNULL(BA.exitDate, NOW())
It s possible this is too many rows, and perhaps you need some other way to handle (for example) only getting the date rather than full datetime. However you should routinely specify ALL the non-aggregating columns of a query in the group by caluse. See MySQL GROUP BY Extension