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From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-118) Lift some DB2 restrictions on DEFAULT values [was: Allow any build-in function as default values in table create for columns]
Date Thu, 14 Jun 2012 19:47:42 GMT

     [ https://issues.apache.org/jira/browse/DERBY-118?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Dag H. Wanvik updated DERBY-118:
--------------------------------

    Attachment: derby-118-limited.status
                derby-118-limited.diff

Attaching a trimmed down patch ("*-limited"), that just lifts those restrictions that are
OK with the standard:

a) remove the restriction on VARCHAR defaults length to 254
b) remove the restriction that a decimal default cannot lose precision (but it can't overflow).
It will generate a warning at insert time, though.

The latter doesn't strike me as very useful (probably more likely it would be an error, so
if you like, I'll omit that one, too).

Rerunning regressions.

                
> Lift some DB2 restrictions on DEFAULT values [was: Allow any build-in function as default
values in table create for columns]
> -----------------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-118
>                 URL: https://issues.apache.org/jira/browse/DERBY-118
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Bernd Ruehlicke
>            Assignee: Dag H. Wanvik
>            Priority: Minor
>         Attachments: derby-118-all-defaults.diff, derby-118-limited.diff, derby-118-limited.status,
derby-118-longvarchar.diff, derby-118.diff, derby-118.stat, derby-118b.diff, derby-118b.stat,
derby-118c.diff, derby-118c.stat
>
>
> It is ok in ij to do a   values char(current_date)   but is is not allowed to use char(current_date)
as default value for clolumns; like for example
> CREATE TABLE DOSENOTWORK (num int, created_by varchar(40) default user, create_date_string
varchar(40) default char(current_date))
> Request: It should be allowed to use any build-in function which return a valid type
as part of the default value spec.
> There was a e-mail thread for this and the core content/answer was:
> Bernd Ruehlicke wrote:
> > 
> > CREATE TABLE DOSENOTWORK (num int, created_by varchar(40) default 
> > user, create_date_string varchar(40) default char(current_date))
> > 
> > give an error as below - any idea why ?!??!
> > 
> The rules for what is acceptable as a column default in Derby say that the only valid
functions are datetime functions. 
>   The logic that enforces this can be seen in the "defaultTypeIsValid" method of the
file:
> ./java/engine/org/apache/derby/impl/sql/compile/ColumnDefinitionNode.java
> The Derby Reference Manual also states this same restriction (albeit rather briefly):
> ----
> Column Default
> For the definition of a default value, a ConstantExpression is an expression that does
not refer to any table. It can include constants, date-time special registers, current schemas,
users, and null.
> ----
> A "date-time special register" here means a date-time function such as "date(current_date)"
in your first example. 
> Since the function "char" is NOT a date-time function, it will throw an error.
> I believe this restriction was put in place as part of the "DB2 compatibility" work was
that done in Cloudscape a while back.
> Hope that answers your question,
> Army

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