Sorting by two different fields

[jkruer01]

Hello everyone. I am trying to create an online forum much like this and I am having problems with the code. I have two different tables( Topic and Reply ), and both of them have a time field in it. I want to sort the topics on the main page by the most recent time. So if the topic has a reply use the time from the last reply but if not use the Time from the Topic table. Can anyone help me with this?

Thanks!

[ereptur]

I assume that you are using an inner join with the two tables.

if you are, you could simply issue a query like the following:

select * from tables as a inner join tables2 as b on a.id=b.id order by b.time, a.time desc;

If b.time doesn't exist it should auto default to using a.time as the order by.

[jkruer01]

Thanks, but unfortunately that didn't work. Now it sorts all of the Topics that have a reply and puts them at the top and then it sorts all of the topics that don't have a reply and puts them to the bottom. To see what I am talking about go to http://www.iuslug.org/~jkruer01/
The order is currently
"The new forum is open (1 reply)"
"This is a test (1 reply)"
"another post (0 replies)"
"This is a test (0 replies)"

But it should be
"another post (0 replies)"
"The new forum is open (1 reply)"
"This is a test (1 reply)"
"This is a test(0 replies)"

Does anyone have any suggestions?