MAX(issue_number)+1 where YEAR(date) = Year(NOW())
I continued to work while waiting for ideas, and have now manage to get a script that work.
I'm getting the next issue number this way:
// Connect to database to get latest issue number from table un_issue
db_connect($dbuser, $dbpassword, $dbdatabase);
$query = "SELECT * FROM un_issue ORDER BY i_id DESC LIMIT 1";
$result = mysql_query($query);
$row = mysql_fetch_row($result);
$next_issue_number = $row[2] + 1;
$previous_issue_date = $row[1];
I didn't think of the problem when two users are adding at the same time since this won't happen in this particular case. But what could I do to avoid the problem in future scripts?
Doing what I wanted to do took six hours and 120 lines of code, all in all, but I learnt a good deal on the way. ;-)
//Anders