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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-2335) Compare character datatypes with different collation ordering.
Date Tue, 15 May 2007 21:29:17 GMT

     [ https://issues.apache.org/jira/browse/DERBY-2335?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Mamta A. Satoor updated DERBY-2335:

    Attachment: DERBY2335_Use_PushDataValueFactory_in_ExpressionClassBuilder_v2_stat.txt

Committed attached patch (DERBY2335_Use_PushDataValueFactory_in_ExpressionClassBuilder_v2_diff.txt)
with revision 538325 and following comments

Made changes such that rather than having a new method in BaseTypeCompiler to push the DVD
on the stack at code generation time, we use the existing method that accomplishes the same
task in ExpressionClassBuilder. The junit tests have run fine with these changes and the stack
trace experienced by Army in DERBY-2335 has been fixed by this fix. The reason for stack trace
was that the lifetime of a BaseTypeCompiler is longer than a single class generation and I
was trying to hold a reference to a declared method from MethodBuilder.describeMethod across
the generated classes. This discussion can be found at 

> 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:
>            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, DERBY2335_More_tests_And_Fix_getNull_v1_diff.txt,
DERBY2335_More_tests_And_Fix_getNull_v1_stat.txt, DERBY2335_Use_LCC_in_ValueNode_v1_diff.txt,
DERBY2335_Use_LCC_in_ValueNode_v1_stat.txt, DERBY2335_Use_PushDataValueFactory_in_ExpressionClassBuilder_v1_diff.txt,
DERBY2335_Use_PushDataValueFactory_in_ExpressionClassBuilder_v1_stat.txt, DERBY2335_Use_PushDataValueFactory_in_ExpressionClassBuilder_v2_diff.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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