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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 Fri, 11 May 2007 21:28:15 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_More_tests_And_Fix_getNull_v1_stat.txt
                DERBY2335_More_tests_And_Fix_getNull_v1_diff.txt

Commited (revision 537296) the attached patch DERBY2335_More_tests_And_Fix_getNull_v1_diff.txt
which addresses 3 issues and adds some tests
1)Easiest first, fixed the javadoc error in WorkHorseForCollatorDatatypes.java
2)CharConstantNode in it's bind method does the collation setting based on the compilation
schema. But it didn't do the switching of it's value from SQLChar/SQLVarchar/SQLLongvarchar/SQLClob
to CollatorSQLChar/CollatoSQLVarchar/CollatoSQLLongvarchar/CollatoSQLClob
if the collation type for it ends up being territory based. By default, the value associated
with CharConstantNode is always UCS_BASIC collation. It should get switched to territory based
and my fix in this class does that job.
3)DataTypeDesciptor.getNull value currently gets the DVD using typeId.getNull(). But we should
check if we are dealing with territory based collation and if yes, then we should change the
DVD type returned by typeId.getNull from
SQLChar/SQLVarchar/SQLLongvarchar/SQLClob to CollatorSQLChar/CollatoSQLVarchar/CollatoSQLLongvarchar/CollatoSQLClob.
My change in DataTypeDescriptor.getNull does that job.
4)In addition, I have added tests in CollationTest class to do some persistent character columns
testing. Some tests are commented out and will be added later.


> 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, DERBY2335_More_tests_And_Fix_getNull_v1_diff.txt,
DERBY2335_More_tests_And_Fix_getNull_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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