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From Apache Wiki <wikidi...@apache.org>
Subject [Db-derby Wiki] Update of "BuiltInLanguageBasedOrderingDERBY-1478" by DanDebrunner
Date Thu, 22 Mar 2007 14:49:42 GMT
Dear Wiki user,

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The following page has been changed by DanDebrunner:
http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478

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  6)For a string literal which is not inside an operation like upper/lower/substring etc,
it's collation type in DTD will be marked UNKNOWN. When such a string literal gets used in
a collation method, it's collation type will be same as the other operand involved in the
collation eg sysColumn1 < 'aaa', then the collation type of 'aaa' will change from UNKNOWN
to UCS_LOCALE at the comparison time. But if the comparison was userColumn1 < 'aaa', then
the collation type of 'aaa' will be that of the collaiton type of userColumn1. As a third
case, if the comparison was between 2 string literals, ie 'aaa' < 'bbb', then the collation
type of each of the string literal will be the COLLATION applicable at the user character
level.
  
+    '''Question''' Does this match the SQL standard?
+ 
  7)As for the character expressions involving CAST, TRIM, UPPER, LOWER, SUBSTRING, CONCATENATE,
the result character datatype will have the same collation type as their operands. 
+ 
+    '''Questions''' What about other character expressions, such as functions? What happens
when CONCATENATE is passed two values with different collations?
  
  8)When a character column is added using CREATE TABLE/ALTER TABLE, make sure that the correct
collate type is populated in the TypeDescriptor's scale field in the SYS.SYSCOLUMNS table.
  

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