subtract two column value

[kazitula]

hi
I have got a table for internet accesswith user ID, it has 3 column user ID, starttime and endtime, i want to make another column which will show how many mins or hours that user was logged in to the internet. can anyone please help me...
thanks
kaz

[dickersonka]

i wouldn't suggest adding an additional column necessarily, but creating a view, that way, your duration will always be in sync with the columns

select USER_ID, START_TIME, END_TIME,
DATE_DIFF(second, START_TIME, END-TIME) AS DURATION_SEC
FROM
InternetAccess

depending on what you need, you can sub in minute, hour, or second amongst others for the datediff

[kazitula]

hi thanks for the reply. but i tired this and it says

"SQL Error: ORA-00904: "DATEDIFF": invalid identifier
00904. 00000 -  "%s: invalid identifier"
*Cause:    
*Action:"

can you please check it?
thanks.

[dickersonka]

you posted this in the mssql forum, are you using oracle then?

if so, post in there