If you have a large database, it may be difficult to export all of its tables at once through phpMyAdmin. The most common reason for this is the timeout limit most web hosting companies set on their shared servers.
Fortunately, there is an easy solution for this issue. Instead of selecting all tables in the database and then exporting them, you should export the large database by selecting only several tables at a time.
This way, if you wish to import the database, you will have to import smaller SQL dumps and thus you will avoid a phpMyAdmin timeout during the import process.