Re: column_info()'s COLUMN_DEF values - literal vs function

On Wed, 27 May 2009 15:40:13 +0100, Tim Bunce <[email protected]>
wrote:

> How does your DBI driver represent a default column value in the results
> returned by the column_info() method?
> 
> Specifically, does it distinguish between default literal strings and
> default functions/expressions?
> 
> Consider the difference between these two column definitions
> 
>     bar1 timestamp not null default 'current_timestamp',
>     bar2 timestamp not null default  current_timestamp,
> 
> or, more generally:
> 
>     foo1 varchar(20) not null default 'current_user',
>     foo2 varchar(20) not null default  current_user,
> 
> This issue has cropped up in relation to a bug Jos has filed against
> DBIx::Class::Schema::Loader: https://rt.cpan.org/Ticket/Display.html?id=46412
> 
> The ODBC 3.0 spec says
> http://web.archive.org/web/20070513203826/http://msdn.microsoft.com/library/en-us/odbc/htm/odbcsqlcolumns.asp
> 
>     The default value of the column. The value in this column should be
>     interpreted as a string *if it is enclosed in quotation marks*.
> 
>     If NULL was specified as the default value, then this column is the word
>     NULL, not enclosed in quotation marks. If the default value cannot be
>     represented without truncation, then this column contains TRUNCATED,
>     with no enclosing single quotation marks. If no default value was
>     specified, then this column is NULL.
> 
>     *The value of COLUMN_DEF can be used in generating a new column
>     definition*, except when it contains the value TRUNCATED.
> 
> (The *emphasis* is mine.)
> 
> So, people, what does your database driver do for these cases?
> Are COLUMN_DEF values for literal defaults returned by column_info()
> enclosed in quotation marks?

Unify, and thus DBD::Unify, does not have support for default values
in CREATE TABLE statements at all, so just tell me what to do. Ignore
or fill with NULL

DBD::CSV is completely depending on SQL::Statement through DBD::File
here, and as DBD::CSV has no concept (yet) of a stored DDD, there is no
real use for it al all.

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