--原始数据：@TA
declare @TA table(id int,MyType varchar(1),Adate datetime,MyEndDate datetime,MySign int)
insert @TA
select 1,'R','2007-8-25',null,0 union all
select 2,'F','2007-8-2',null,0 union all
select 3,'F','2007-8-26',null,0 union all
select 4,'F','2007-8-19',null,0 union all
select 5,'R','2007-8-19',null,0 union all
select 6,'R','2007-8-1',null,0

update @TA set
MyEndDate=
    case (@@datefirst-1+datepart(weekday,Adate))%7
        when 0 then MyEndDate
        else dateadd(day,(case MyType when 'R' then 1 else 3 end)*7-(@@datefirst-1+datepart(weekday,Adate))%7,ADate)
    end,
MySign=
    case (@@datefirst-1+datepart(weekday,Adate))%7
        when 0 then 1
        else MySign
    end

select * from @TA

/*

id          MyType Adate                                                  MyEndDate                                              MySign      
----------- ------ ------------------------------------------------------ ------------------------------------------------------ ----------- 
1           R      2007-08-25 00:00:00.000                                2007-08-26 00:00:00.000                                0
2           F      2007-08-02 00:00:00.000                                2007-08-19 00:00:00.000                                0
3           F      2007-08-26 00:00:00.000                                NULL                                                   1
4           F      2007-08-19 00:00:00.000                                NULL                                                   1
5           R      2007-08-19 00:00:00.000                                NULL                                                   1
6           R      2007-08-01 00:00:00.000                                2007-08-05 00:00:00.000                                0

（所影响的行数为 6 行）

*/

------解决方案--------------------
不好意思,應該是8-
update ta set MyEndDate = (CASE WHEN datepart(dw,Adate)= 1 then MyEndDate  
                          ELSE  
                               CASE WHEN MyType =   'R  ' THEN DATEADD(dd,8-DATEPART(dw,Adate),Adate) 
                               CASE WHEN MyType =   'F  ' THEN DATEADD(dd,14+8-DATEPART(dw,Adate),Adate) END            
                          END ), 
             MySign = (CASE WHEN datepart(dw,Aate)= 1 THEN 1 ELSE mySign END )  


------解决方案--------------------
SQL code
declare @TA table(id int,MyType varchar(1),Adate datetime,MyEndDate datetime,MySign int)
insert @TA
select 1,'R','2007-8-25',null,0 union all
select 2,'F','2007-8-2',null,0 union all
select 3,'F','2007-8-26',null,0 union all
select 4,'F','2007-8-19',null,0 union all
select 5,'R','2007-8-19',null,0 union all
select 6,'R','2007-8-1',null,0

update t
set 
    [MyEndDate]=case when MyType='R' and (DATEPART(Weekday,Adate)+@@DATEFIRST-1)%7<7 then DATEADD(Day,7-(DATEPART(Weekday,Adate)+@@DATEFIRST-1)%7,Adate)
                    when MyType='F' and (DATEPART(Weekday,Adate)+@@DATEFIRST-1)%7<7 then  DATEADD(Day,7-(DATEPART(Weekday,Adate)+@@DATEFIRST-1)%7