Rule 5) in the collation wiki page says:
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5)Result character string types from UPPER, LOWER, TRIM(LTRIM, RTRIM),
SUBSTR will have the same collation as their operand. This comes from
SQL spec Section 6.29 <string value function> Syntax Rules 8, 8, 11d, 4
respectively). The collation derivation will be implicit.
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http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478
I don't see where the last sentence comes from: "The collation
derivation will be implicit.".
That doesn't seem to be correct, if the operand has collation explicit
or none shouldn't that be carried through to the result of the character
string function? The rules in 6.29 that are quoted by 5) above just say
the type is the type of the operand which includes the derivation,
right? I don't see anything in 6.29 about asserting implicit derivation.
I haven't looked at the code to see what is implemented, just wanted to
raise this as a possible issue.
Dan.
