首先使用 UNION ALL 从您想要的 2 个表中获取所有行，然后聚合：

SELECT session_id,SUM(points) AS total_points
FROM (
  SELECT session_id,spent_points AS points
  FROM session_details 
  WHERE session_id IN ("-Meagevy6y9ukbmFXvB7","-Meak6dG9iqvHWfAGQvy") 
  UNION ALL
  SELECT session_id,price_points
  FROM template_sales 
  WHERE session_id IN ("-Meagevy6y9ukbmFXvB7","-Meak6dG9iqvHWfAGQvy") 
) t
GROUP BY session_id

你就快到了：

WITH union_rows (session_id,points) AS (
        SELECT session_details.session_id,session_details.spent_points
          FROM session_details
         WHERE session_details.session_id IN ('-Meagevy6y9ukbmFXvB7','-Meak6dG9iqvHWfAGQvy')
         UNION ALL
        SELECT template_sales.session_id,template_sales.price_points
          FROM template_sales
         WHERE template_sales.session_id IN ('-Meagevy6y9ukbmFXvB7','-Meak6dG9iqvHWfAGQvy')
     )
SELECT session_id,SUM(points) AS total_sum
  FROM union_rows
 GROUP BY session_id
;

如果您有旧版本的 MySQL，没有 WITH clause 支持，请改用派生表。

session_id 过滤器可以在 CTE 术语之外完成，但之后您也可以携带所有其他行，直到过滤器被处理。

也许您可以使用 session_id 在这两个表之间进行 JOIN。 之后，您可以将两个属性相加。

它会是这样的：

SELECT session_details.session_id,SUM(SD.SPENT_POINTS + TSS.PRICE_POINTS ) AS total_sum_session 
FROM session_details SD
JOIN template_sales.session_id TSS ON SD.SESSION_ID = TSS.SESSION_ID
WHERE SD.session_id IN ("-Meagevy6y9ukbmFXvB7","-Meak6dG9iqvHWfAGQvy") 
GROUP BY SD.session_id 

试试这个：

SELECT A.session_id,SUM(A.Total) AS Total
FROM 
(
  SELECT session_details.session_id,session_details.spent_points AS Total
  FROM session_details 
  WHERE session_details.session_id IN ("-Meagevy6y9ukbmFXvB7","- 
  Meak6dG9iqvHWfAGQvy") 

  UNION ALL

  SELECT template_sales.session_id,template_sales.price_points AS Total
  FROM template_sales 
  WHERE template_sales.session_id 
  IN ("-Meagevy6y9ukbmFXvB7","-Meak6dG9iqvHWfAGQvy") 
) AS A
GROUP BY A.session_id