我想根据项目id和通道更新同一个sql表中的sum。对于总通道=总和（通道1+通道2）

id | Channel       | Project_id | Column1 | Column 2 | Column 3 |
-----------------------------------------------------------
1    Total Channel   PR1           10         10        10
2    Channel 1       PR1            5         5          5
3    Channel 2       PR1            5         5          5
4    Total Channel   PR2            20        40         30
5    Channel 1       PR2            10        20         15
6    Channel 2       PR2            10        20         15
7    Total Channel   PR3            30        50         10
8    Channel 1       PR3            15        25         5
9    Channel 2       PR3            15        25         5

我正在尝试下面的查询，但此查询中有问题

UPDATE 
    results AS r 
JOIN
    ( SELECT   project_id, 
               SUM(Column1) AS sum_column1,
               SUM(Column2) AS sum_column2,
               SUM(Column3) AS sum_column3,
      FROM     results 
      WHERE    channel <> 'Total Channel' and project_id=@project_id
      GROUP BY project_id
    ) AS grp
   ON  
       grp.project_id = r.project_id 
SET 
   r.column1 = grp.sum_column1,
   r.column2 = grp.sum_column2,
   r.column3 = grp.sum_column3
WHERE 
   r.project_id = @project_id and r.channel='Total Channel';