DATEPART

DATEPART allows you to retrieve components of a date.

You can extract also YEAR, MONTH, DAY, HOUR, MINUTE, SECOND.

   DATEPART(YEAR, d)    DATEPART(MONTH, d)
   DATEPART(DAY, d)     DATEPART(HOUR, d)
   DATEPART(MINUTE, d)  DATEPART(SECOND, d)

In this example you get the year and the month from the date whn.

SELECT whn
      ,DATEPART(YEAR, whn)  AS yr
      ,DATEPART(MONTH, whn) AS mnth
  FROM eclipse

SELECT whn
      ,EXTRACT(YEAR FROM td)  AS yr
      ,EXTRACT(MONTH FROM td) AS mnth
  FROM eclipse