[Phpmyadmin-devel] about the central columns table
Smita
kumarismita62 at gmail.com
Sun May 25 15:27:13 CEST 2014
On Sun, May 25, 2014 at 5:15 PM, Marc Delisle <marc at infomarc.info> wrote:
> 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.
>
> Yeah, agree.
> 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.
>
>
While adding new columns in tbl3, user could have used the central list to
add the "phone_number" column, that way he wont end up writing wrong
name/definition. But Yes, validating table against central list is another
option that we can add . And can be applied to existing columns in the
system and also to those that have not been added through PMA UI.
--
Marc Delisle | phpMyAdmin
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