>>>>>Hi,
>>>>>
>>>>>How do you SUM number of days difference between two DateTime type fields as following:
>>>>>
>>>>>

>>>>>select SUM( DATETIME1 - DATETIME2) AS NUMDAYS
>>>>>

>>>>

>>>>SELECT SUM(DATEDIFF(dd, Date1, Date2)) AS NumDays
>>>>

>>>
>>>Borislav,
>>>
>>>I am trying to understand the DATEDIFF() function better. Do I understand correctly that the 1st parameter "dd" really has no literal meaning? That is, you can name this parameter anything and it won't change the result?
>>
>>It has, it means days :-)
>>As Naomi said it means we wand to get difference in days. Check BOL to see the other values of the first parameter.
>
>Yes, this is what I did (after posting the question instead of before :)); I read about DATEDIFF() in BOL and it all is clear now.
>
>Thank you.


BTW the same abbreviations are valid for DATEADD() also :-)