Thanks for help! its was almost right, next code worked well



function onInit()

local nodeChar = window.getDatabaseNode();
local nodeCharSheetMain = nodeChar.getParent().getParent();
Debug.chat("nodeCharSheetMain: ", nodeCharSheetMain);

local nodePath = nodeCharSheetMain.getPath();
Debug.chat("nodePath: ", nodePath);

local nFight = DB.getValue(nodePath .. ".Fight_current", 0);
Debug.chat("nFight: ", nFight);

end