how to calculate the difference between two columns with datatype timestamp : i am having a two columns login,logout with values "2019-08-07 20:37:12" in login column and "2019-08-07 21:14:16" in logout column.
i want the difference between time values from login and logout columns

sql

SELECT logintime,CONVERT(varchar(6),DATEDIFF(second, login, logout)/3600)
+ ':'
+ RIGHT('0' + CONVERT(varchar(2),(DATEDIFF(second, login,logout) % 3600) / 60), 2)
+ ':'
+ RIGHT('0' + CONVERT(varchar(2),DATEDIFF(second, login, logout) % 60), 2) AS 'HH:MM:SS' from face_login_logout

expected result is '2019-08-07 01:23:04 '