让我帮你拆解一下子查询里的问题，你确实猜对了核心问题出在子查询的FROM/JOIN语法上，还有一些逻辑细节需要调整：

你的简化SQL里的几个关键错误 #

1. 括号与别名位置错误
   你把别名AS tt放在了ON tbl_Ts_mkv_atp.ID_Ts = tbl_Ts_base_atp.ID_Ts后面，这是语法错误。别名应该绑定在你要命名的表（或表组合）末尾，而且你的JOIN括号没有正确闭合，导致数据库无法解析表关系。
2. 冗余关联主表
   子查询里没必要再次JOINtoday_atp，这会让关联逻辑混乱。子查询只需要通过tbl_Ts_base_atp.ID_T和主查询的today_atp.TOUR做关联即可。
3. 多余的ORDER BY
   标量子查询只需要返回单个聚合值，ORDER BY在这里完全没用，反而可能引发语法报错。

修正后的简化版SQL #

SELECT 
    today_atp.TOUR,
    (
        SELECT Sum(tbl_Ts_mkv_atp.FS)
        FROM tbl_Ts_base_atp
        INNER JOIN tbl_Ts_mkv_atp ON tbl_Ts_base_atp.ID_Ts = tbl_Ts_mkv_atp.ID_Ts
        WHERE 
            tbl_Ts_base_atp.DATE_T > Date()-2000 
            AND tbl_Ts_base_atp.DATE_T < Date()
            AND tbl_Ts_base_atp.ID_T = today_atp.TOUR -- 关联主查询的TOUR字段
        GROUP BY tbl_Ts_base_atp.ID_T -- 确保每个ID_T返回唯一求和值
    ) AS SumOfFS
FROM today_atp

整合到原主查询的完整SQL（标量子查询方式） #

SELECT 
    tours_atp.NAME_T,
    today_atp.TOUR,
    today_atp.ID1,
    odds_atp.K1,
    today_atp.ID2,
    odds_atp.K2,
    (
        SELECT Sum(tbl_Ts_mkv_atp.FS)
        FROM tbl_Ts_base_atp
        INNER JOIN tbl_Ts_mkv_atp ON tbl_Ts_base_atp.ID_Ts = tbl_Ts_mkv_atp.ID_Ts
        WHERE 
            tbl_Ts_base_atp.DATE_T > Date()-2000 
            AND tbl_Ts_base_atp.DATE_T < Date()
            AND tbl_Ts_base_atp.ID_T = today_atp.TOUR
        GROUP BY tbl_Ts_base_atp.ID_T
    ) AS SumOfFS
FROM 
    (players_atp 
    INNER JOIN (players_atp AS players_atp_1 
        INNER JOIN (today_atp 
            INNER JOIN odds_atp ON (today_atp.TOUR = odds_atp.ID_T_O) 
                AND (today_atp.ID1 = odds_atp.ID1_O) 
                AND (today_atp.ID2 = odds_atp.ID2_O) 
                AND (today_atp.ROUND = odds_atp.ID_R_O)
        ) ON players_atp_1.ID_P = today_atp.ID2
    ) ON players_atp.ID_P = today_atp.ID1) 
INNER JOIN tours_atp ON today_atp.TOUR = tours_atp.ID_T 
WHERE 
    (((tours_atp.RANK_T) Between 1 And 4) 
    AND ((today_atp.RESULT)="") 
    AND ((players_atp.NAME_P) Not Like "*/*") 
    AND ((players_atp_1.NAME_P) Not Like "*/*") 
    AND ((odds_atp.ID_B_O)=2)) 
ORDER BY tours_atp.NAME_T;

更高效的派生表JOIN方式（推荐大数据量场景） #

如果你的数据量较大，用派生表+LEFT JOIN的方式性能会更好，避免逐行执行子查询：

SELECT 
    tours_atp.NAME_T,
    today_atp.TOUR,
    today_atp.ID1,
    odds_atp.K1,
    today_atp.ID2,
    odds_atp.K2,
    COALESCE(fs_sum.SumOfFS, 0) AS SumOfFS -- 无匹配时返回0而非NULL
FROM 
    (players_atp 
    INNER JOIN (players_atp AS players_atp_1 
        INNER JOIN (today_atp 
            INNER JOIN odds_atp ON (today_atp.TOUR = odds_atp.ID_T_O) 
                AND (today_atp.ID1 = odds_atp.ID1_O) 
                AND (today_atp.ID2 = odds_atp.ID2_O) 
                AND (today_atp.ROUND = odds_atp.ID_R_O)
        ) ON players_atp_1.ID_P = today_atp.ID2
    ) ON players_atp.ID_P = today_atp.ID1) 
INNER JOIN tours_atp ON today_atp.TOUR = tours_atp.ID_T 
LEFT JOIN (
    SELECT 
        tbl_Ts_base_atp.ID_T,
        Sum(tbl_Ts_mkv_atp.FS) AS SumOfFS
    FROM tbl_Ts_base_atp
    INNER JOIN tbl_Ts_mkv_atp ON tbl_Ts_base_atp.ID_Ts = tbl_Ts_mkv_atp.ID_Ts
    WHERE 
        tbl_Ts_base_atp.DATE_T > Date()-2000 
        AND tbl_Ts_base_atp.DATE_T < Date()
    GROUP BY tbl_Ts_base_atp.ID_T
) AS fs_sum ON fs_sum.ID_T = today_atp.TOUR
WHERE 
    (((tours_atp.RANK_T) Between 1 And 4) 
    AND ((today_atp.RESULT)="") 
    AND ((players_atp.NAME_P) Not Like "*/*") 
    AND ((players_atp_1.NAME_P) Not Like "*/*") 
    AND ((odds_atp.ID_B_O)=2)) 
ORDER BY tours_atp.NAME_T;

内容的提问来源于stack exchange，提问作者Jossy