Mysql 更新计算值时返回NULL的联接嵌套子查询

我试图解决“您不能在FROM子句中指定更新的目标表”MySQL错误，这意味着我有一个嵌套的子查询（临时表）。注意，在我进入实际的

更新之前，我正在尝试让
选择
工作

我得到的是一个分类账表，在该表中，我试图使用
活动单位
（该行的开头）和活动单位中的每一个额外调整（同一表中有一个付款行和多个调整行，通过佣金ID和计划编号关联）查找关联行的计算单位总数。它们按
month\u num
分组。因此，如果它是
active\u units=18
，并且有三个调整行，一个是
active\u units\u chg=-2
，那么我应该以
18+-2=16
结束

当我这样做时：

SELECT
   active_units
 , active_units_chg
 , active_units_total
 , CRM_commission_payments.active_units + (
    SELECT SUM(active_units_chg)
    FROM CRM_commission_payments AS cp
    WHERE cp.CRM_commissions_item_id = CRM_commission_payments.CRM_commissions_item_id
    AND cp.schedule_a_no = CRM_commission_payments.schedule_a_no
    AND cp.month_num = CRM_commission_payments.month_num
    AND cp.item_active = 1
) AS active_units_cal1
FROM CRM_commission_payments
WHERE CRM_commission_payments.payment_type = 'payment'
AND CRM_commission_payments.CRM_quotes_item_id = 2457

active\u units\u cal1
对于该行是正确的。但是，当我使用嵌套的
JOIN
'd子查询执行此操作时，对于
active\u units\u calc.calc\u chg
，我会得到
NULL
：

SELECT
   active_units
 , active_units_chg
 , active_units_total
 , CRM_commission_payments.active_units + (
    SELECT SUM(active_units_chg)
    FROM CRM_commission_payments AS cp
    WHERE cp.CRM_commissions_item_id = CRM_commission_payments.CRM_commissions_item_id
    AND cp.schedule_a_no = CRM_commission_payments.schedule_a_no
    AND cp.month_num = CRM_commission_payments.month_num
    AND cp.item_active = 1
) AS active_units_cal1
 , active_units_calc.calc_chg
FROM CRM_commission_payments
LEFT JOIN  (
     SELECT
        source.calc_chg
      , source.CRM_commissions_item_id
      , source.schedule_a_no
      , source.month_num
     FROM CRM_commission_payments AS cp1
     INNER JOIN (
          SELECT
             SUM(active_units_chg) AS calc_chg
           , cp.CRM_commissions_item_id
           , cp.schedule_a_no
           , cp.month_num
          FROM CRM_commission_payments AS cp
          WHERE cp.item_active = 1
     ) AS source
     WHERE source.CRM_commissions_item_id = cp1.CRM_commissions_item_id
     AND source.schedule_a_no = cp1.schedule_a_no
     AND source.month_num = cp1.month_num
) AS active_units_calc ON (
   active_units_calc.CRM_commissions_item_id = CRM_commission_payments.CRM_commissions_item_id
   AND active_units_calc.schedule_a_no = CRM_commission_payments.schedule_a_no
   AND active_units_calc.month_num = CRM_commission_payments.month_num
)
WHERE CRM_commission_payments.payment_type = 'payment'
AND CRM_commission_payments.CRM_quotes_item_id = 2457

我做错了什么？
由于顶部按预期工作，如果拉出左连接查询，它是否也会返回预期结果？它似乎是挂起的地方。不管联接子查询是否存在，字段子查询都可以工作。连接子查询是我真正需要的工作。