This can happen as the HTTP post size is limited to a smaller number. The best way to restore your SQL database is by logging into SSH. Be sure that you've already created your MySQL Database from inside of the control panel.
- Upload your SQL file to your root directory /home/username/
- Load up PuTTy or your favourite terminal client.
- Run the following command
mysql -u your_mysql_user -p your_mysql_db < /home/username/sqlfile.sql
- Enter in your password and press enter.
Once completed it will return to bash.