a Null check for a single record

Hi,
I have a table that may contains Null filled columns.
I have a SP that do Update and insert.
How can i do a null check to avoid trying to update null fields?
let say Type_1 column is null, I need a condition that will do a quick check (single record is sufficient) to see that it has null value and to skip the update command:

CREATE PROCEDURE Lan_Insert_Data_Type
as
DECLARE @.Single_Rec int
Begin

-- ??? HERE comes the condition --

UPDATE Data_type
SET Product_Num = LanTable.ProductNum,
Data =LanTable.Type_1
FROM Data_Type p
JOIN LanTable
ON Lantable.ProductNum = p.Product_num where p.Data_Type =1

Thanks

Yossi--Try This

CASE When Type_1 IS NULL
Then
--Do nothing
SET @.Single_Rec = @.Single_Rec

ELSE

UPDATE Data_type
SET Product_Num = LanTable.ProductNum,
Data =LanTable.Type_1
FROM Data_Type p
JOIN LanTable
ON Lantable.ProductNum = p.Product_num where p.Data_Type =1

END|||Originally posted by eschapir
--Try This

CASE When Type_1 IS NULL
Then
--Do nothing
SET @.Single_Rec = @.Single_Rec

ELSE

UPDATE Data_type
SET Product_Num = LanTable.ProductNum,
Data =LanTable.Type_1
FROM Data_Type p
JOIN LanTable
ON Lantable.ProductNum = p.Product_num where p.Data_Type =1

END
Thaks for the reply
but its not working,
maybe i missed some thing|||/* something like this ? */

if not exists(
select *
FROM Data_Type p
JOIN LanTable
ON Lantable.ProductNum = p.Product_num
where p.Data_Type=1 and LanTable.Type_1 is null
)
UPDATE Data_type
SET Product_Num = LanTable.ProductNum,
Data =LanTable.Type_1
FROM Data_Type p
JOIN LanTable
ON Lantable.ProductNum = p.Product_num where p.Data_Type =1|||Originally posted by ispaleny
/* something like this ? */

if not exists(
select *
FROM Data_Type p
JOIN LanTable
ON Lantable.ProductNum = p.Product_num
where p.Data_Type=1 and LanTable.Type_1 is null
)
UPDATE Data_type
SET Product_Num = LanTable.ProductNum,
Data =LanTable.Type_1
FROM Data_Type p
JOIN LanTable
ON Lantable.ProductNum = p.Product_num where p.Data_Type =1

Works great...
Thanks mate