>Hi,
>
>I created a computed column in a table of SQL Server 2005. The column name is DaysOver. The formula in the Computed Column Specificaion is [Date1]-[Date2]. The type of the column is empty. Does this column always return an integer? Because I use it in the SQL select as following:
>
>

>select * from MyTable where DaysOver > 10
>

>
>And the returned query has the correct rows. But what if one of the DateTime columns (Date1 or Date2) is NULL? What will be returned?

I hope you're using DATEDIFF function. The datediff function returns an integer. The type of derived column is determined by SQL Server itself and it may be tricky.

You can also try adding CAST function if you want to ensure a specific type.