Re: MySQLs' "FOREIGN KEYS¨

Oops! really sorry , the tables were not of InnoDB type
that could have supported FKEYS. *Will post again* once
i get to put FKEYS properly on InnoDB tables.

Still in that case also the beast should tell loudly about
whats going on behind.

Mallah.

Jan Wieck wrote:

> Rajesh Kumar Mallah wrote:
>
>>
>> MySQL does not thinks 0 to be a valid integer data .
>> Although 0 is not present in master table
>> it allows inserting in a referencing table
>> as though 0 == NULL . This is really funny (dangerous)
>
>
> What does it do if you have a NOT NULL constraint on the FK column and
> insert 0?
>
>
> Jan
>
>>
>>
>> mysql> alter table slave add foreign key (id2) references master(id);
>> Query OK, 6 rows affected (0.00 sec)
>> Records: 6 Duplicates: 0 Warnings: 0
>>
>>
>> mysql> select * from master;
>> Empty set (0.00 sec)
>>
>> mysql>
>>
>>
>> mysql> select * from slave;
>> +------+
>> | id2 |
>> +------+
>> | 0 |
>> | 0 |
>> | 0 |
>> | 0 |
>> | 0 |
>> | 0 |
>> +------+
>> 6 rows in set (0.00 sec)
>
>
>