If you run following script in this SQL Command. Itwill give you same results and no performance difference. It will return the current server time.
SELECT CURRENT_TIMESTAMP;
SELECT {fn NOW()};
SELECT getdate();
The GETDATE() function returns the current date and time from the SQL Server.
If you want to take records within a certain date range.
SYNTAX:
SELECT * FROM TABLENAME WHERE DateTime <= getdate();
SELECT * FROM post WHERE Postedon <= getdate();