Power up Uno with external 5vdc power supplies.

I'm newbis. I'm using the external 5vdc to power up the Uno. So the question is can we download the program to Uno board with the enternal power supplies still connect to the Uno board and the board on operation.

Yes.

Ok.tq. does't need any usb shield?

zainimechanical: Doesn't need any usb shield?

No. The Arduino UNO has a USB connector right on it. You just need a Type A to Type B cable, typically used for a USB printer.