how to get total working hours per day?

CREATE TABLE #emp_time (

CardNo varchar(50),

IODate datetime,

EntryTime datetime,

ExitTime datetime

)

insert into #emp_time (CardNo,IODate,EntryTime,ExitTime) select top 10 A.CardNo,A.IODate,( select top 10 CAST(A.IOTime as datetime) - CAST(A.IOTime AS datetime) as EntryTime from Tble_IOData A where IOStatus ='Entry'), (select top 10 CAST(A.IOTime as datetime) - CAST(A.IOTime AS datetime) as ExitTime from Tble_IOData A where IOStatus ='Exit') from Tble_IOData A