You can use SUM() with CASE statement.

SELECT SoccerTeam, Player, Goals,
    CASE WHEN SUM(Goals) OVER (PARTITION BY SoccerTeam) > 0 THEN 'y' ELSE 'n' END AS GoalsInTeam
FROM YourTable;

You can use a window function inside a CASE expression for this. I've put * in the query because you said you had lots of other columns. You should replace the star with the list of columns you want in the query. You can also put columns after the 'goals_in_team' column if you prefer.

SELECT  *, --replace with your list of columns in preferred order
        CASE 
            WHEN SUM(goals) OVER (PARTITION BY soccer_team) > 0 
            THEN 'y' 
            ELSE 'n' 
        END AS goals_in_team
FROM results;