如何在SQL Server中的每个循环使用？

Question

I have a table tblEmpDetail which contains a column CreatedDate .

I want to add 72 hours to each created date, so if the created date is 2012-07-14 07:21:19.180 then I want the output to be 2012-07-17 07:21:19.180 .

Can someone let me know how can I accomplish to this?

Actually what I want to do is to go to each row then check if the

getdate() - createddate 

is equal to or less than 72 hours; then I need to add 72 hours to createddate . Otherwise I want that column to be null. I am pasting my code that what I have done.

Declare @PassedTime datetime
set @PassedTime= DATEDIFF(HH,Createddate, GETDATE())

if CONVERT(varchar(20),@PassedTime,108)>=CONVERT(varchar(20),'72:00:00',108)
begin
    select empno,empName,CreatedDate,dateadd(HH,72,CreatedDate)BD from tblEmpDetail 
end
else
begin
   select empno,empName,CreatedDate,'' as BD from tblEmpDetail
end

Answer 1

No looping is required.

SQL Server excels at doing "set based" queries.

To get a projection:

select
    CreatedDate,
    DateAdd(hour, 72, CreatedDate) [NewDate]
from
    tblEmpDetail

To update the table permanently:

update
    tblEmpDetail
set
    CreatedDate = DateAdd(hour, 72, CreatedDate)

If you MUST have a loop, you can use a cursor:

declare cur cursor fast_forward read_only for
select
    CreatedDate,
    DateAdd(hour, 72, CreatedDate) [NewDate]
from
    tblEmpDetail

-- here, you would use the cursor.

More information on cursors here: http://msdn.microsoft.com/en-us/library/ms180169.aspx

EDIT

Your query above can be done in a set based way like this:

select
    CreatedDate,
    CASE
        WHEN DateAdd(hour, 72, CreatedDate) <= GetDate() THEN NULL
        ELSE DateAdd(hour, 72, CreatedDate)
    END [NewDate]
from
    tblEmpDetail