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'm not sure why your existing query would take over 5s for 40,000 rows.

I just tried the following query against a table with 100,000 rows and it returned in less than 0.1s.

SELECT DISTINCT DATEADD(day, 0, DATEDIFF(day, 0, your_date_column))
FROM your_table

(Note that this query probably won't be able to take advantage of any indexes on the date column, but it should be reasonably quick, assuming that you're not executing it dozens of times per second.)