Le 2014-05-24 11:03, Smita a écrit :
On Sat, May 24, 2014 at 7:49 PM, Marc Delisle <marc@infomarc.info mailto:marc@infomarc.info> wrote:
Hi Smita, I have a doubt, looking at the structure you chose for this table: db_name column_list This structure implies that, for any change, you have to load a potentially big row, decode it and encode it. Imagine that there are hundreds or thousands of column definitions for this db. I suggest something like: db_name column_name column_attributesYeah, agree. Thanks, It would be better to keep this. :-). I have a question: If we have "id interger(11) not null auto_increment" already existing in central list, should we allow to add another column "id integer(20) not null auto_increment" ? If we don't allow then we can also keep structure like maybe: db_name column_name column_type column_collation column_isNull column_extra
- Smita
In a central list, there should be only one column named "id" (but this choice of name would be problematic, of course; a better choice would be "customer_id").
Another example is "phone_number"; which is reused in the customer table and in the salesperson table. You might want to always use CHAR(25) for phone numbers.
So it's a good idea to split the attributes into separate columns like in your example. The default value could be there too.