In the table below, how do I get just the most recent row with id=1
based on the signin
column, and not all 3 rows?
+----+---------------------+---------+
| id | signin | signout |
+----+---------------------+---------+
| 1 | 2011-12-12 09:27:24 | NULL |
| 1 | 2011-12-13 09:27:31 | NULL |
| 1 | 2011-12-14 09:27:34 | NULL |
| 2 | 2011-12-14 09:28:21 | NULL |
+----+---------------------+---------+
Use the aggregate MAX(signin)
grouped by id. This will list the most recent signin
for each id
.
SELECT
id,
MAX(signin) AS most_recent_signin
FROM tbl
GROUP BY id
To get the whole single record, perform an INNER JOIN
against a subquery which returns only the MAX(signin)
per id.
SELECT
tbl.id,
signin,
signout
FROM tbl
INNER JOIN (
SELECT id, MAX(signin) AS maxsign FROM tbl GROUP BY id
) ms ON tbl.id = ms.id AND signin = maxsign
WHERE tbl.id=1