Creating a pop-up after onInputProcessing

I have a table. I let the user select a row. Then they click a button to basically open an existing record. At this point I check the database for the status of the record in the onInputProcessing section.

If the record contains a certain status the user would like a pop-up message (like an alert) either before going to the next screen. Or I could display some sort of message at the start of the next page. Has anyone had to do this or know of a good weblog to make a pop-up message occur?

It doesn't work to use the onClientClick because I have to go read information out of the database and decide wether or not to show the message.

Thanks,

Anthony