How to quickly select DISTINCT dates from a Date/Time field, SQL Server

Question

I am wondering if there is a good-performing query to select distinct dates (ignoring times) from a table with a datetime field in SQL Server.

My problem isn\'t getting

Answer 1

I've used the following:

CAST(FLOOR(CAST(@date as FLOAT)) as DateTime);

This removes the time from the date by converting it to a float and truncating off the "time" part, which is the decimal of the float.

Looks a little clunky but works well on a large dataset (~100,000 rows) I use repeatedly throughout the day.