Problem with connector between Arduino and MS SQL Server

Using Arduino Interfacing w/ Software on the Computer
20

Used: C:\Users\Fer\AppData\Roaming\Arduino15\packages\MightyCore\hardware\avr\2.0.0\libraries\Ethernet
Not used: C:\Program Files (x86)\Arduino\libraries\Ethernet

MightyCore? It's time you told us what board you are compiling for.