您的查询似乎不完整，必须使用 UNION ALL 为了得到完整的总数（f）2或更多的球员有相同的分数 UNION DISTINCT 将消除这些行）：

SELECT
    SUM( points )
FROM (
    SELECT
        points
    FROM player
    JOIN team ON player.full_name = team.player1
    WHERE team.team_id = 8
    AND week = 9
    UNION ALL
    SELECT
        points
    FROM player
    JOIN team ON player.full_name = team.player2
    WHERE team.team_id = 8
    AND week = 9
    UNION ALL
    SELECT
        points
    FROM player
    JOIN team ON player.full_name = team.player3
    WHERE team.team_id = 8
    AND week = 9
    UNION ALL
    SELECT
        points
    FROM player
    JOIN team ON player.full_name = team.player4
    WHERE team.team_id = 8
) d

但我相信你的团队表格需要修改以获得更好的效率
请注意，使用 UNION = UNION DISTINCT i、 e.如果省略，则假定为“不同”。
这可能更有效：

SELECT
    SUM( player.points )
FROM player
WHERE player.full_name IN (
    SELECT distinct
        case when cj.n = 1 then team.player1
             when cj.n = 2 then team.player2
             when cj.n = 3 then team.player3
             when cj.n = 4 then team.player4
        end
    FROM team
    cross join (
       select 1 as n union all
       select 2 as n union all
       select 3 as n union all
       select 4 as n
       ) cj
    WHERE team.team_id = 8
    )
AND player.week = 9    ;