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https://issues.apache.org/jira/browse/DERBY-2335?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12494635
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Mamta A. Satoor commented on DERBY-2335:
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Army, thanks for spending some time testing with XML. I spent couple hrs and
unfortunately can't pinpoint right away what is causing this. I tried using
-Dderby.debug.true=DumpClassFile but looks like if there is an error during the
code generation and we don't generate any class for the problem query. It will
be nice if there was an even partial dump of what ever code has been generated
for the query even if it runs into problem because that would help with
debugging. Oh well..
I will put this on my todo list but in the meantime, if you/anyone find any
more problems, do let me know.
> Compare character datatypes with different collation ordering.
> --------------------------------------------------------------
>
> Key: DERBY-2335
> URL: https://issues.apache.org/jira/browse/DERBY-2335
> Project: Derby
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 10.3.0.0
> Reporter: Mamta A. Satoor
> Assigned To: Mamta A. Satoor
> Attachments:
> DERBY2335_correct_collation_for_constants_persistent_column_v1_diff.txt,
> DERBY2335_correct_collation_for_constants_persistent_column_v1_stat.txt,
> DERBY2335_fix_stringCompare_Method_CollatorSQLxxx_classes_v1_diff.txt,
> DERBY2335_fix_stringCompare_Method_CollatorSQLxxx_classes_v1_stat.txt
>
>
> The parent task DERBY-1478 will enable users to have a different collation
> order for user-defined character datatypes compared to UNICODE based
> collation, UCS_BASIC, used by system tables. This sub-task is added to handle
> the case where a comparison is made between character datatypes with
> different collation order.
> For instance
> Let's say, a database is created to use a territory based collation for
> character types. And say there is a userSchema schema in that database which
> has a table tableInfo with column tablename defined as VARCHAR. This
> tableInfo.tablename will have territory based collation assoicated with it.
> And say this column is then compared with a VARCHAR column in SYS schema,
> then how will the comparison happen, since the 2 columns being compared have
> different collation associated with them?
> select * from sys.systables and userSchema.tableInfo where
> systables.tablename = tableInfo,tablename
> Thanks to Rick for taking the time out on this issue. He had following
> suggestion
> </Rick comment start>
> "As I read part 2 of the SQL Standard, it looks like you need a CAST in order
> to compare 2 strings which have different collations bound to them. Both
> string operands must have the same collation--that is my reading of Syntax
> rule 3b in section 9.13. Sections 6.12 and 6.1 explain how to cast the
> operands so that you can compare them. I think you need to write an
> expression like this:
> WHERE userStringCol = CAST ( systemStringCol AS VARCHAR COLLATE
> userStringColumnsCollation )
> Here's an example I googled up:
> http://docs.openlinksw.com/virtuoso/sqlrefDATATYPES.html. Hope this helps.
> </Rick comment end>
> When this task is taken up, it would be good to explore Rick's suggestion.
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