The easiest and possibly the best idea of importing data from another database to a new database is the CSV export. OpenErp gives you this feature in the versions 6.1 and 7.0.

Following is the example on how you can export customers to a csv file:

1. First go to the Customers, select all and click on the Export link on the side menu on the right of your screen.
2. The Export Wizard will appear, select Import Compatible Export as Export Type, (see image export1.png) and CSV as Export Formats.

3. Select all the fields you wish to export, use with Ctrl key to select multiple fields, and click to Add, and click on Export to File.

4. You will see a new file(res.partner(1).csv) getting downloaded.

5. Now in your new database go the Customers, and click on the Import link just above the Export link.

6. The Import Wizard will appear(see image import.png), upload the CSV file you just downloaded and click on the Import button.

7. Check you customers(See image imported_customers.png).