Creating a Table Where Date has to be Now OR Future

[Shadowayara]

How do i get a Table with the Collum Date That Looks if The Date that was put in is NOW or in the FUTURE
This is What i got Right now.


CREATE TABLE uitgifte
(uitgiftenr SERIAL PRIMARY KEY,
klantnr INT,
datum DATE >= NOW,
FOREIGN KEY (klantnr) REFERENCES klant (klantnr))

The Date Idk how to Make it Check automatically for Dates Beyond.