How to populate a table with a range of dates?

I need a MySQL table to hold ALL DATES between 2011-01-01 and 2011-12-31. I have created a table with one column names "_date", type DATE.

With what query can I populate the table with all the desired dates (instead of having to enter them by hand)?

Try this:

DROP PROCEDURE IF EXISTS filldates;
DELIMITER |
CREATE PROCEDURE filldates(dateStart DATE, dateEnd DATE)
BEGIN
  WHILE dateStart <= dateEnd DO
    INSERT INTO tablename (_date) VALUES (dateStart);
    SET dateStart = date_add(dateStart, INTERVAL 1 DAY);
  END WHILE;
END;
|
DELIMITER ;
CALL filldates('2011-01-01','2011-12-31');

Here's the SQL Fiddle to play with it: http://sqlfiddle.com/#!2/65d13/1

EDIT (to check if date already exists) as asked by Andrew Fox.

CREATE PROCEDURE filldates(dateStart DATE, dateEnd DATE)

BEGIN

DECLARE adate date;

    WHILE dateStart <= dateEnd DO

        SET adate = (SELECT mydate FROM MyDates WHERE mydate = dateStart);

        IF adate IS NULL THEN BEGIN

            INSERT INTO MyDates (mydate) VALUES (dateStart);

        END; END IF;

        SET dateStart = date_add(dateStart, INTERVAL 1 DAY);

    END WHILE;

END;//

Here's the SQL Fiddle to play with it: http://sqlfiddle.com/#!2/66f86/1