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https://issues.apache.org/jira/browse/DERBY-6340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13779752#comment-13779752
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Dyre Tjeldvoll commented on DERBY-6340:
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Hi Rick, thanks for the feedback. I'll incorporate your suggestions into a new
rev of the fs.
Wrt. your questions: I'm not very familiar with various parts of the sql
standard so I should probably be more careful about what I assert. So when I
said that the exiting UDTs are non-standard, I really meant to say that I
cannot see that the grammar, as specified in Part 2, section 11.51
<user-defined type definition> permits the current CREATE TYPE syntax. I'll
have a look at SQL/JRT.
Wrt. FINAL I agree that it is meaningless for distinct types, but as I read the
grammar it is nevertheless permitted. I had not considered the fact that FINAL
is not currently a reserved word. If we need to add it as a reserved word just
to allow this syntax, then I agree that it makes sense to omit it.
Wrt. grammar rules in light gray. It really means that those clauses are not
permitted because of the rule mentioned in the comment. Or that was the
intention, I see now that I have forgotten to update the first grammar snippet:
[ <user-defined type option list> ] -- S028
is incorrectly gray, but should have been green.
[ <method specification list> ] -- S023
is supposed to be gray, but the comment should have been -- CR 12
Because conformance rule 12) of 11.51 states: "Without Feature S023, “Basic
structured types”, conforming SQL language shall not contain a <method
specification list>."
But yes, it also implies that they will not be implemented.
> Add support for CREATE TYPE AS <existing type> (synonym types)
> --------------------------------------------------------------
>
> Key: DERBY-6340
> URL: https://issues.apache.org/jira/browse/DERBY-6340
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Reporter: Dyre Tjeldvoll
> Assignee: Dyre Tjeldvoll
> Attachments: CreateTypeAs_fs_draft.html
>
>
> The SQL standard (2003) chapter 11.41 <user-defined type definition> allows
> the creation of synonyms or aliases for an existing type: CREATE TYPE AS
> <predefined type>. By allowing this in Derby we would simplify migration
> from, and interoperation with, other databases.
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