IS NULL returns Empty set, but I have empty items

[Norman Khine]

Hello,
I don't know what I am missing, but I have this:

mysql> SELECT url FROM product WHERE url IS NULL;
Empty set (0.05 sec)

mysql> SELECT url FROM product WHERE product_Id = 67;
+------+
| url  |
+------+
|      |
+------+
1 row in set (0.00 sec)

what goes with this, how can i ensure that this is NULL?

here is the table structure

http://pastie.org/1066140

thanks for any insight.


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