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Start a terminal session using character set big5.
In gnome-terminal:
Terminal -> Character Coding -> Traditional Chinese (big5)
Make sure everything works fine:
LANG=zh_TW.big mysql --default-character-set=big5 --table << END
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SET NAMES big5;
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SELECT HEX(''),HEX('乂');
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END
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should return:
+----------+-----------+
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| HEX('?') | HEX('乂') |
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+----------+-----------+
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| C840 | C940 |
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+----------+-----------+
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If you get a different output, then something is wrong with the terminal
character set settings.
Notice, the character with the Big5 code C840 is unassigned
(does not have a Unicode mapping), while the character with
the Big5 code c940 is assigned.
Now create an ENUM with non-assigned and assigned characters:
LANG=zh_TW.big mysql --default-character-set=big5 --table test << END
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SET NAMES big5;
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DROP TABLE IF EXISTS t1;
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CREATE TABLE t1 (a ENUM('','乂') CHARACTER SET big5);
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SHOW CREATE TABLE t1;
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INSERT INTO t1 VALUES (''),('乂');
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SELECT HEX(a),a FROM t1;
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END
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The output will be:
+-------+-----------------------------------------------------------------------------------------------------------------+
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| Table | Create Table |
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+-------+-----------------------------------------------------------------------------------------------------------------+
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| t1 | CREATE TABLE `t1` (
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`a` enum('?','乂') CHARACTER SET big5 DEFAULT NULL
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) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
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+-------+-----------------------------------------------------------------------------------------------------------------+
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+--------+------+
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| HEX(a) | a |
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+--------+------+
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| C840 | |
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| C940 | 乂 |
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+--------+------+
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Notice, the unassigned character got converted to question mark
in the SHOW CREATE output, but INSERT/SELECT actually work fine.
Now dump and restore:
mysqldump --socket=/tmp/mysql.sock test >t1.sql
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mysql -e "drop table t1" test
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mysql test <t1.sql
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mysql -e "select hex(a),a from t1" test
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The output will be:
+--------+------+
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| hex(a) | a |
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+--------+------+
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| 3F | ? |
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| C940 | 乂 |
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+--------+------+
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The unassigned character got lost.
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