From: Peter Zaitsev
Date: July 27 2000 12:38pm
Subject: Re: Query with having does not work properly.
List-Archive: http://lists.mysql.com/mysql/45652
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> Your patch looks ok, but I have now split the date add/sub code
> to make it faster and shorter;  This will be in 3.23.22 (I don't
> submit a patch now as I want to test this throughly before releasing it!)

I'm not shure if this is allready a source of this problems, but currently
such thing is happening:

mysql> select  date_add(0, interval 7 day)<20000101;
+--------------------------------------+
| date_add(0, interval 7 day)<20000101 |
+--------------------------------------+
|                                 NULL |
+--------------------------------------+
1 row in set (0.01 sec)

mysql> select  0<date_sub(20000101,interval 7 day);
+-------------------------------------+
| 0<date_sub(20000101,interval 7 day) |
+-------------------------------------+
|                                   1 |
+-------------------------------------+
1 row in set (0.00 sec)


Therefore this selects are mathematically equal.  Even the first result may
be right, but if so the second one should be exactly the same :)