[
https://issues.apache.org/jira/browse/DERBY-118?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13285484#comment-13285484
]
Knut Anders Hatlen commented on DERBY-118:
------------------------------------------
I don't see any obvious problems with making Derby's type conversion in DEFAULT
clauses more liberal. That is, except that it might trick users into writing
non-portable SQL. I don't feel strongly for or against any of the alternatives,
so I'd be fine both with leaving it as it is and with making the conversions
more symmetric.
However, the patch only partially addresses the asymmetry, as far as I can see.
It adds special handling of conversions to string data types, but INSERT seems
to accept other conversions too, like float->int, which we currently don't
allow in DEFAULT clauses. If we decide that we want to allow implicit type
conversion in DEFAULT clauses, we should probably do it for all types.
> 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.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
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
