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https://issues.apache.org/jira/browse/DERBY-2967?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12531956
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Daniel John Debrunner commented on DERBY-2967:
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Looking carefully at the SQL Standard - section 8.5 SR 3 c) ii) 4) then
currently (I think) Derby's LIKE with TERRITORY_BASED collation is not being
implemented correctly.
For a pattern like 'aa' (norway) or 'ch' (spain) then the SQL standard
indicates that LIKE operates a character at a time. So the pattern is not the
combination of 'aa' or 'ch', but two separate characters 'a' 'a' or 'c' 'h' .
The collation is only used when comparing this single ( 'exactly 1 (one)' )
character.
MySQL indicates this as well, stating LIKE performs matching on a per-character
basis, thus it can produce different results to the = comparison operator.
E.g. 'AA' LIKE 'Å' is FALSE, but 'AA' = 'Å' is TRUE
This would indicate that during LIKE processing a CollationElementIterator
should only ever be created on a single character,
though this does go back to Kathey's question of what is a single character
(see DERBY-3080). There seem to be three forms
that could be called a single character:
1) A simple single Unicode codepoint such a 'Å' U+212B
2) A single Unicode codepoint followed by one or more combining marks, e.g.
U+0041 U+030A
3) A contraction, where two or more characters *sort as if* they were a single
base character (e.g. CH in spanish)
Unicode TR10 I think is saying that 1) and 2) are single characters, but 3) is
not.
(MySQL reference:
http://dev.mysql.com/doc/refman/4.1/en/string-comparison-functions.html )
> Single character does not match high value unicode character with collation
> TERRITORY_BASED
> -------------------------------------------------------------------------------------------
>
> Key: DERBY-2967
> URL: https://issues.apache.org/jira/browse/DERBY-2967
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.4.0.0
> Reporter: Kathey Marsden
> Assignee: Mamta A. Satoor
> Attachments: DERBY2967_offset_based_diff_Oct02_07.txt,
> DERBY2967_offset_based_stat_Oct02_07.txt, fullcoll.out,
> patch2_setOffset_fullcoll.out, patch2_with_setOffset_diff_Sep2007.txt,
> patch2_with_setOffset_stat_Sep2007.txt, step1_iteratorbased_Sep1507_diff.txt,
> step1_iteratorbased_Sep1507_stat.txt, temp_diff.txt, temp_stat.txt,
> TestFrench.java, TestNorway.java
>
>
> With TERRITORY_BASED collation '_' does not match the character \uFA2D. It
> is the same for english or norwegian. FOR collation UCS_BASIC it matches
> fine. Could you tell me if this is a bug?
> Here is a program to reproduce.
> import java.sql.*;
> public class HighCharacter {
> public static void main(String args[]) throws Exception
> {
> System.out.println("\n Territory no_NO");
> Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
> Connection conn =
> DriverManager.getConnection("jdbc:derby:nordb;create=true;territory=no_NO;collation=TERRITORY_BASED");
> testLikeWithHighestValidCharacter(conn);
> conn.close();
> System.out.println("\n Territory en_US");
> conn =
> DriverManager.getConnection("jdbc:derby:endb;create=true;territory=en_US;collation=TERRITORY_BASED");
> testLikeWithHighestValidCharacter(conn);
> conn.close();
> System.out.println("\n Collation USC_BASIC");
> conn = DriverManager.getConnection("jdbc:derby:basicdb;create=true");
> testLikeWithHighestValidCharacter(conn);
> }
> public static void testLikeWithHighestValidCharacter(Connection conn) throws
> SQLException {
> Statement stmt = conn.createStatement();
> try {
> stmt.executeUpdate("drop table t1");
> }catch (SQLException se)
> {// drop failure ok.
> }
> stmt.executeUpdate("create table t1(c11 int)");
> stmt.executeUpdate("insert into t1 values 1");
>
> // \uFA2D - the highest valid character according to
> // Character.isDefined() of JDK 1.4;
> PreparedStatement ps =
> conn.prepareStatement("select 1 from t1 where '\uFA2D' like ?");
> String[] match = { "%", "_", "\uFA2D" };
> for (int i = 0; i < match.length; i++) {
> System.out.println("select 1 from t1 where '\\uFA2D' like " + match[i]);
> ps.setString(1, match[i]);
> ResultSet rs = ps.executeQuery();
> if( rs.next() && rs.getString(1).equals("1"))
> System.out.println("PASS");
> else System.out.println("FAIL: no match");
> rs.close();
> }
> }
> }
> Mamta made some comments on this issue in the following thread:
> http://www.nabble.com/Single-character-does-not-match-high-value-unicode-character-with-collation-TERRITORY_BASED.-Is-this-a-bug-tf4118767.html
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