获取数据库表中列的最大值

Question

I'm trying to get the max value of a column in a database table.

This is my PHP:

$st = mysql_fetch_assoc(mysql_query("SELECT max(`version`) FROM `remembers` WHERE id='$id'"));
$version = $st['version'] + 1;

So that should get the current version of id and then update it but adding 1 to it. But $st['version'] seems to be returning 0 when in the database the current highest is 1

Am I doing this wrong? Is there a better way to archive this?

Answer 1

You have to alias the MAX() selection in SQL in order to reference it in PHP:

SELECT max(`version`) AS version FROM ...

Also, mysql_fetch_assoc returns an array of arrays, so you cannot simply reference $st['version'] directly. Instead, you can change your PHP to:

$st = mysql_fetch_row(mysql_query("SELECT max(`version`) AS version FROM `remembers` WHERE id='$id'"));
$version = $st[0] + 1;