I know that the private key is important. Lose it, I will lose my bitcoin.

I download Bitcoin Core, install it and get my wallet but I don't know how to dump my private key in my wallet.

I search and see a command dumpprivkey address, it can be used but if I have 100 bitcoin addresses and each one have bitcoin, what to do?

Use the command 100 times is not a good idea because with the 100 times I can make mistakes.

Thank you and happy weekend.