> Say for example one employee's entry and exit time may be multiple in a
> day that's
> why I need only one date and time column based on this i will do rest
> calculation.
>  
> because i don't know how many times employee might have gone out side and
> again came in for the same day. so, as per this i think one date and one
> time column is enough.
>  
>  
> Now as per following columns how i will calculate the total time employee
> had worked for a day (i.e. for each day)
>  
> 1) EmpNo Varchar(15)
> 2) dtDate Date
> 3) tmTime Time

As others have already said, use a timstamp to replace your separate date and time fields.
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