Friend System[SQL]

Hello people!
such is how I can do that, two player wants to be friends, type command pl. /friend ID and from then on they see each other's names.(ShowNameTagPlayer) and save mysql.
something like this:
John_Bellic friends:
Tom_Wick
Johnny_Depp
Gordon_Big

Tom_Wick friends:
John_Bellic

And player connect load friends.

I tried to somehow solve,but it did not work. The save failed, shownametag succeeded only.
If you can help with this please comment!


(Bad english sorry)