Peter Zaitsev wrote:
>
> > 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)
This is correct behaviour. The first argument to date_add()/date_sub() has to be
a date. If it is not, MySQL will try to convert it to a date - 0 does not
convert to a date so date_add(0, interval 7 day) evaluates to NULL. In the
second case, 20000101 can be converted to a valid date: 2000-01-01
--
Sasha Pachev
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