Best approach to remove time part of datetime in SQL Server

Question

Which method provides the best performance when removing the time portion from a datetime field in SQL Server?

a) select DATEADD(dd, DATEDIFF(dd, 0, getdate(         


        

Answer 1

If possible, for special things like this, I like to use CLR functions.

In this case:

[Microsoft.SqlServer.Server.SqlFunction]
    public static SqlDateTime DateOnly(SqlDateTime input)
    {
        if (!input.IsNull)
        {
            SqlDateTime dt = new SqlDateTime(input.Value.Year, input.Value.Month, input.Value.Day, 0, 0, 0);

            return dt;
        }
        else
            return SqlDateTime.Null;
    }