Updating the last row MYSQL - mysql

Question

I want to update the last row in a mysql table
UPDATE logend
SET endsecs = endsecs+'$moretime'
WHERE id = (SELECT id FROM logend ORDER BY id DESC LIMIT 1)
But it doesn't work, because of this error:
ERROR 1093 (HY000): You can't specify target table 'logend' for update in FROM clause

Answer 1

In MySql you can't use the updated table in a subquery the way you do it.
You would get the error:
You can't specify target table 'logend' for update in FROM clause
What you can do is an UPDATE with ORDER BY and LIMIT:
$sql = "UPDATE logend SET endsecs=endsecs+'$moretime' ORDER BY id DESC LIMIT 1";

Answer 2

Can't you just get the max(id) and update that?
$sql = "UPDATE logend SET endsecs=endsecs+'$moretime' WHERE id = (
SELECT id FROM (
SELECT MAX(id) FROM logend) AS id
)";

Answer 3

Here's another solution: a self-join, to find the row for which no other row has a greater id.
Also, you should really not interpolate POST inputs directly into your SQL statement, because that exposes you to SQL injection problems. Use a query parameter instead.
$moretime = $_POST['moretime'];
$sql = "
UPDATE logend AS l1
LEFT OUTER JOIN logend AS l2 ON l1.id < l2.id
SET l1.endsecs = l1.endsecs + ?
WHERE l2.id IS NULL";
$stmt = $mysqli->prepare($sql);
if (!$stmt) {
trigger_error($mysqli->error);
die($mysqli->error);
}
$stmt->bind_param("s", $moretime);
$ok = $stmt->execute();
if (!$ok) {
trigger_error($stmt->error);
die($stmt->error);
}