c# - Error in Updating a table using Stored procedure -

in stored procedure there error occured. 'format' not recognized built in function name

set ansi_nulls on set quoted_identifier on go  alter procedure [dbo].[attendance_updatebyemployee_id] @employee_id int, @atdate datetime, @fnlogged bit, @anlogged bit, @logtime varchar(10), @logouttime varchar(10)  begin     select @atdate     set nocount on;         update mst_attendance set fnlogged=@fnlogged,    anlogged=@anlogged,logtime=@logtime,logouttime=@logouttime     employeeid=@employee_id , atdate = format(@atdate,'mm/dd/yyyy')  select * mst_attendance atdate=@atdate , employeeid=@employee_id   end 

try

 convert(varchar(10), @atdate, 101) [mm/dd/yyyy] 

however, surely atdate column should datetime?