How do you test if something is older than 3 months?

I have been having some trouble to select the rows of my t开发者_如何学JAVAable which has a date of 3 months prior of today. I tried using DATE(NOW() - INTERVAL 3 MONTH) in my where clause, but no luck. How do I check in SQL Server if a item is older than 3 months?

  UPDATE[TCTdb].[dbo].[Stock]
     SET[Warehouse] = 'old'
   WHERE [ManufacturedDate] <= DATE(NOW() - INTERVAL 3 MONTH)

---

Your syntax appears to be wrong.

That should be

UPDATE[TCTdb].[dbo].[Stock]
    SET[Warehouse] = 'old'
WHERE [ManufacturedDate] <= DATEADD(mm, -3, GETDATE())

---

Use dateadd().

update [TCTdb].[dbo].[Stock]
set [WareHouse] = 'old'
where [ManufacturedDate] < dateadd(month,-3,getdate())

I suggest dateadd() over datediff() because I think you're going to get unexpected results using datediff() with the month datepart.

Consider that the following statements both return 3:

select datediff(month, '1/1/2011','4/1/2011')
select datediff(month, '1/1/2011','4/30/2011')

Either works in this particular case... Just keep that behavior in mind.

---

The DATEDIFF function should be helpful to you:

http://msdn.microsoft.com/en-us/library/ms189794.aspx

UPDATE[TCTdb].[dbo].[Stock]
    SET[Warehouse] = 'old'
    WHERE DATEDIFF(month, [ManufacturedDate], GETDATE()) > 3

---

try out DATEDIFF:

SELECT 
    case 
        when DATEDIFF(month, '2005-12-31' , '2006-04-01 ') > 3
        then 'yes'

        else 'no'

    end

Hope that helps,

John