Hi,
Every exchange adding a new btc, eth, token address on the exchange website.
I think they need some private key to set the transaction on this websites.
So is this private key stored in a normal database?
And is this safe?
Actually it is very safe if you store your coins in exchange wallet because usually they using cold storage to store all of coins and tokens.
But it is not impossible to be hacked, there were some exchanges have been hacked. So it will be the best for us to using our own wallet if we want to hold for long time.