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

CAST(round(cast(getdate()as real),0,1) AS datetime)

This method does not use string function. Date is basically a real datatype with digits before decimal are fraction of a day.

this I guess will be faster than a lot.