declare @a varchar(14)
declare @c varchar(6)
declare @b datetime

set @a ='20111101000000'
set @c = substring(@a,1,8)
print @c
set @b = convert(datetime,@c,120)
print @b

declare @a varchar(14)
declare @c varchar(8)  --楼主注意这里，截取的是8位，但定义了6位。
declare @b datetime

set @a ='20111101000000'
set @c = substring(@a,1,8)
print @c
set @b = convert(datetime,@c,112)
print @b

------解决方案--------------------
SQL code

declare @a varchar(14)
declare @c varchar(8)
declare @b datetime

set @a ='20111101000000'
set @c = substring(@a,1,8)
print @c
set @b = convert(VARCHAR(10),@c,120)
print CONVERT(VARCHAR(10),@b,120)

------解决方案--------------------
SQL code

declare @a varchar(14)
declare @c varchar(6) 
declare @b datetime 


set @a ='20111101000000' 




print CONVERT(VARCHAR(23),CONVERT(DATETIME,LEFT(@a,8)),121)

------解决方案--------------------
SQL code

declare @a varchar(14)


set @a ='20111101000000' 




print CONVERT(VARCHAR(23),CONVERT(DATETIME,LEFT(@a,8)),121)