date not inserting - shows 0000-00-00 after insert

I am trying to insert date to a mysql table. The SQL query I used to create the table is as follows:

CREATE TABLE IF NOT EXISTS DDD(id INT NOT NULL AUTO_INCREMENT PRIMARY KEY UNIQUE, 
    datecolumn DATE NOT NULL , 
    open FLOAT, 
    high FLOAT, 
    low FLOAT, 
    close FLOAT, 
    volume INT)

I am inserting the data with the following SQL statement:

INSERT INTO DDD(datecolumn, open, high, low, close, volume)
VALUES(2011-05-26, 12.09, 13.31, 12.05, 13.09, 1293441)

After that when I select and view the data the entries in the datecolumn is


0000-00-00

I have tried the solution from

importing CSVs into MySQL table leaves date fields as 0000-00-00

...but it resulted in the following error:

ERROR 1064 (42000): You have an error in your SQL syntax; 
check the manual that corresponds to your MySQL server version 
for the right syntax to use near 'datecolumn DATE' at line 1

after the following query,

ALTER TABLE db.DDD MODIFY datecolumn datecolumn DATE;

I am a novice in SQL and learning now. Could anyone shed some light, what it is that I am doing wrong?

Put the date into quotation marks:

INSERT INTO DDD(datecolumn, open, high, low, close, volume) 
VALUES('2011-05-26', 12.09, 13.31, 12.05, 13.09, 1293441)

MySQL will have silently done some mathematics with 2011-05-26 and got its knickers in a twist.

It does warn you though:

mysql> insert into d VALUES(2011-05-26);
Query OK, 1 row affected, 1 warning (0.01 sec)

mysql> show warnings;
+---------+------+-----------------------------------------------------+
| Level   | Code | Message                                             |
+---------+------+-----------------------------------------------------+
| Warning | 1264 | Out of range value for column 'datecolumn' at row 1 |
+---------+------+-----------------------------------------------------+
1 row in set (0.00 sec)

mysql>

Without using quotes, MySQL is essentially inserting the integer 1980 ( which is 2011 minus 05 minus 26) as a date, as it treats it as mathematics:

mysql> select 2011-05-26;
+------------+
| 2011-05-26 |
+------------+
|       1980 |
+------------+
1 row in set (0.00 sec)

mysql>

StackExchange Database Administrators Q#174346, answer score: 12