[Phpmyadmin-devel] about the central columns table

[Marc Delisle]

Le 2014-05-25 06:48, Smita a écrit :
> 
> 
> On Sat, May 24, 2014 at 11:53 PM, Smita <kumarismita62 at gmail.com
> <mailto:kumarismita62 at gmail.com>> wrote:
> 
> 
> 
>     On Sat, May 24, 2014 at 10:25 PM, Marc Delisle <marc at infomarc.info
>     <mailto:marc at infomarc.info>> wrote:
> 
>         Le 2014-05-24 12:16, Smita a écrit :
>         >
>         >
>         > On Sat, May 24, 2014 at 9:24 PM, Marc Delisle
>         <marc at infomarc.info <mailto:marc at infomarc.info>
>         > <mailto:marc at infomarc.info <mailto:marc at infomarc.info>>> wrote:
>         >
>         >     Le 2014-05-24 11:03, Smita a écrit :
>         >     >
>         >     >
>         >     > On Sat, May 24, 2014 at 7:49 PM, Marc Delisle
>         <marc at infomarc.info <mailto:marc at infomarc.info>
>         >     <mailto:marc at infomarc.info <mailto:marc at infomarc.info>>
>         >     > <mailto:marc at infomarc.info <mailto:marc at infomarc.info>
>         <mailto:marc at infomarc.info <mailto:marc at 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_attributes
>         >     >
>         >     > Yeah, 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").
>         >
>         > So We'll allow only unique column name. If same column name with
>         > different definition tried to add we just show the column name
>         (with
>         > defination) already exist?
> 
>         Yes; eventually I guess that in your project, there will be a way to
>         directly view the central list and change column definitions.
> 
>     Yeah, I need to make a page to manage central columns, there users
>     can view complete list of columns and edit some if they want.
> 
>         >
>         >     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.
>         >
>         > Ok, thanks. We'll keep default as well.
> 
> 
> Hi Marc,
> I redesigned the database as discussed.  I completed the adding columns
> part but I got stuck when came to deletion. I have a question.
> Let say I have two tables tbl1 and tbl2, both table has a common column
> name "phone_number". So If user selects both tables and asks to add
> unique columns to central list, then we are gonna add just one
> "phone_number" , let say we add the column/definition "phone_number"
> from tbl1. now let say user select tbl2 and ask to remove columns from
> central list. What should it do ? should it remove the column
> "phone_number" from central list or not ? as "phone_number" was added
> from tbl1.  but "phone_number" exists in tbl2 as well.
> 
> - Smita

I say we should remove it from the central list. It's up to the user, to
use the feature in a correct way.

Anyway, say the user added phone_number in tbl3 but never used any
central column option on tbl3. phpMyAdmin won't know that this
phone_number in tbl3 possibly has a different definition, unless there
is an option to manually validate all the tables against the central list.


-- 
Marc Delisle | phpMyAdmin