MySQL select MAX(datetime) not returning max value
Try like this:
SELECT d.id, d.computer, d.app, d.version, d.build, a.installed
FROM data d
INNER JOIN (
SELECT computer, app, max(DATE) AS installed
FROM data
GROUP BY computer, app
) a ON a.computer = d.computer AND a.app = d.app
WHERE placement = 'xxx'
The inner query is getting you the max(date) for each pair of computer and app, then you just join with that to get the rest of the information.
Try by casting the Datetime field
SELECT
id,
computer,
app,
version,
build,
MAX(cast(date as Datetime)) AS installed
FROM
data
WHERE
placement = 'xxx'
GROUP BY
app, computer, id, version, build
;