[DERBY-2668] At the time of compilation of a comparison operation, if the collation types of the operands do not match, then we should throw a meaningful error message.

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 10.3.1.4
• Fix Version/s: 10.3.1.4, 10.4.1.3
• Component/s: SQL
• Assignee: Katherine Marsden
• Reporter: Mamta A. Satoor
• Created: 18/May/07 06:25
• Updated: 21/Jan/11 17:50
• Resolved: 06/Aug/07 17:01

Description

In Derby 10.3, we are adding a new feature (DERBY-1478) which will allow character string types to have a territory based collation (except for persistent character string type columns from system schema). When 2 character types are compared, they should have the same collation type associated with them. If not then Derby 10.3 will throw an exception. Currently, in Derby 10.3 codeline, the exception thrown is something like "ERROR 42818: Comparisons between 'VARCHAR' and 'CHAR' are not supported." but this error message is misleading. The error is really for collation mismatch. We should fix following error so it indicates the real reason behind the exception.

eg sql
ij> connect 'nodb;create=true;territory=no;collation=TERRITORY_BASED';
ij> select * from sys.systables where tablename = 'T1';
ERROR 42818: Comparisons between 'VARCHAR' and 'CHAR' are not supported.

Issue Links

• is duplicated by: DERBY-2866 Improve error message when comparing user table and system table columns if collation doesn't match
• relates to: DERBY-1478 Add built in language based ordering and like processing to Derby
• relates to: DERBY-2599 Set correct collation type and derivation on DataTypeDescriptor(DTD).