If you can only upload large databases using phpMyAdmin, you may have encountered the size limit, or you may have encountered php timeouts and file sizes; not all have access to their server through shell or can change php time limits and file upload sizes. The answer is Big Dump. It is a free programme with a web interface that uploads the database in chunks. I recently used it for uploading a Dolphin database to an Arvixe hosted site where phpMyAdmin was having issues though restarts was turned on.
BigDump: Staggered MySQL Dump Importer can be found at http://www.ozerov.de/bigdump/
