Question ethernetcard

Hello I’m new into this. Get a UNO and a ethernet shield.

so here my questions
Ethernet shield does not have an MAC Address. I used one from an old device but still no connection after uploading with the file i attach.

the folder structure in the Program says user/name/documents/arduino
but the programm still goes to Prog…files(x86)/Arduino
How is this sturcture to understand ?

If the sketch for the Ethernet card is uploades and i upload another sketh it will regardless ovewrite the Ethernet sketch ?

Also how can I read those datas from the Arduino, i.e with a sql server ? do I need to set up an own database or how is this mostly handled. I guess not everyone has an sql server running for this purpose

Sorry a lot of questions but after 1 Day playing arround mor questions than answers so far

Thanks

(moderator: updated title)

sketch_sep06b.ino (1.99 KB)

Ethernet.begin(mac, ip, gateway, subnet);

You are missing the DNS Server address. See: https://www.arduino.cc/en/Reference/EthernetBegin