问SQL:如何使用具有以下组的子查询更新多个值

EN

;WITH cte_update as (
    Select 
        row_date,
        logid,
        Interval,
        sum(availtime)/count(availtime) as avail_dist
    from 
        table 
    group by 
        row_date,
        logid,
        Interval )

update t
set 
    t.avail_distribution = cte.avail_dist
from 
    table as t
    inner join cte_update as cte 
        on t.row_date = cte.row_date 
        and t.logid = cte.logid 
        and t.interval = cte.interval

UPDATE a
SET a.avail_distribution = b.val
FROM TableName a INNER JOIN
    ( Select  row_date,logid,Interval,
            sum(availtime)/count(availtime) val
    from  [Table] group by row_date,logid,Interval
    ) b ON a.row_date = b.row_date AND
        a.logid = b.logid AND
        a.Interval = c.Interval

Declare @Data Table
(
    row_date datetime,
    logid int,
    type int,
    Interval int,
    availtime float,
    avail_distribution float
);

Insert Into @Data(row_date,logid,type,Interval,availtime) Values 
('9/25/2013', 122, 4, 850, 640),
('9/25/2013', 122, 5, 850, 0),
('9/25/2013', 122, 7, 850, 0),
('9/26/2013', 122, 4, 850, 500),
('9/26/2013', 122, 5, 850, 0),
('9/26/2013', 122, 7, 850, 0);


;WITH CTE
as
(
    Select *, Avg(availtime) Over (partition by row_date,logid,Interval) 
    as value_of_avail_distribution from @Data
)
Update CTE Set avail_distribution = value_of_avail_distribution

select * from @Data