This article shows how to change database table prefix in the SQL file.
Open the dump.sql file from “sources” (make sure to unzip archived folder first) folder with any text editor. You can use NotePad++, Dreamweaver or Sublime Text.
Do a Find and replace (usually with the CTRL+H hotkeys) and change all the instances of default jos_ prefix to your custom database tables prefix. You can check for your own prefix in Joomla admin panel at the System -> Global Configuration -> Server -> Database Settings section, look for the Database Tables Prefix option value.
When done editing, save the changes and import the modified SQL file into your Joomla database, you can find out database name under Database Settings section mentioned above.