Re: postgresql vs mysql

[Steve Crawford <scrawford(at)pinpointresearch(dot)com>]

Ron Johnson wrote:
> On 02/21/07 18:09, Erick Papadakis wrote:
>> How would you like to use a database that has nuances like these --
>> http://forums.mysql.com/read.php?20,141120,141120#msg-141120
> 
> Huh?
> 
> A blank string (does that mean '' or ' '?) is not NULL, so of
> *course* it should pass the NOT NULL constraint.
> 
> Or am I missing something?
> 

Not sure what the OP was getting at but of course an empty string is not
the same as a NULL. You have to follow that MySQL forum thread a few
messages to see the real screwup. Upon learning that an empty string is
not the same a a NULL, he adds a constraint:

ALTER TABLE `tbl`
CHANGE `col`
`col` VARCHAR( 3 ) CHECK (`col` <>'')
NOT NULL

Unfortunately for him, this does not work either. The reason is
clarified in the following message:

"Currently MySQL accepts CHECK syntax but does not implement them. You
can enforce such a rule at database level with a trigger, or at
application level as another contributor suggested."

Huh?

Cheers,
Steve