如何使一个表中的时间加上一个整数天数形成一个新时间?

[seaxiao]

有二个表：表1是id号和开始时间，表2是id号和持续天数，我想把表1中的开始时间加上表2中的持续时间(天为单位),写入到表2结束时间内？或查询出开始时间+持续时间也行.sql语句应该怎么写？
table1(id,starttime)
----------------
id | starttime
1 | 2010-4-1
2 | 2010-5-10
----------------
table2(id,duration,endtime)
-----------------------------
id|duration|endtime
1| 2 |
1| 5 |
2| 7 |
--------------------------

[playwarcraft]

dateadd(day,1,getdate())

[playwarcraft]

update table2
set endtime=dateadd(day,duration,starttime)
from table1,table2
where table1.id=table2.id

[Mr_Nice]

--> 测试数据：[table1]
if object_id('[table1]') is not null drop table [table1]
create table [table1]([id] int,[starttime] datetime)
insert [table1]
select 1,'2010-4-1' union all
select 2,'2010-5-10'
--> 测试数据：[table2]
if object_id('[table2]') is not null drop table [table2]
create table [table2]([id] int,[duration] int,[endtime] sql_variant)
insert [table2]
select 1,2,null union all
select 1,5,null union all
select 2,7,null

select * from [table1]
select * from [table2]


SELECT B.id,A.starttime,B.duration,[comp]=DATEadd(d,B.duration,A.starttime)
FROM dbo.table1 A
INNER JOIN dbo.table2 B ON B.id = A.ID

/*
id	starttime	duration	comp
1	2010-04-01 00:00:00.000	2	2010-04-03 00:00:00.000
1	2010-04-01 00:00:00.000	5	2010-04-06 00:00:00.000
2	2010-05-10 00:00:00.000	7	2010-05-17 00:00:00.000*/

[dawugui]

update table2
set endtime = dateadd(dd,duration,n.starttime)
from table2 m , table1 n where m.id = n.id

[老黎]

select 
    b.starttime, [endtime] = dateadd(day, a.duration, b.starttime)
from
    table2 a
    left join table1 b
on a.id = b.id

[dawugui]

create table [table1]([id] int,[starttime] datetime)
insert [table1]
select 1,'2010-4-1' union all
select 2,'2010-5-10'
create table [table2]([id] int,[duration] int,[endtime] datetime)
insert [table2]
select 1,2,null union all
select 1,5,null union all
select 2,7,null

update table2
set endtime = dateadd(dd,duration,n.starttime)
from table2 m , table1 n where m.id = n.id

select * from table2

drop table table1, table2

/*
id          duration    endtime                                                
----------- ----------- ------------------------------------------------------ 
1           2           2010-04-03 00:00:00.000
1           5           2010-04-06 00:00:00.000
2           7           2010-05-17 00:00:00.000

（所影响的行数为 3 行）


*/

[seaxiao]

非常感谢各位，学习了。

[--小F--]

update
 table2
set
 endtime=dateadd(dd,duration,starttime)
from 
 table1 join table2
on
 table1.id=table2.id