MySQL - Do Not Pass This Way Again(grimoire.ca)

    mysql: create table data (token_a varchar(10), token_b varchar(10));
	Query OK, 0 rows affected (0.05 sec)

    mysql: insert into data (token_a, token_b) values ('A', 'A');
	Query OK, 1 row affected (0.01 sec)

    mysql: insert into data (token_a, token_b) values ('A', 'B');
	Query OK, 1 row affected (0.00 sec)

    mysql: insert into data (token_a, token_b) values ('B', 'B');
	Query OK, 1 row affected (0.00 sec)

    mysql: insert into data (token_a, token_b) values ('B', 'A');
	Query OK, 1 row affected (0.00 sec)

    mysql: select * from data group by token_a;
	+---------+---------+
	| token_a | token_b |
	+---------+---------+
	| A       | A       |
	| B       | B       |
	+---------+---------+
	2 rows in set (0.00 sec)

        SQL_MODE =
           ALLOW_INVALID_DATES, ANSI_QUOTES, ERROR_FOR_DIVISION_ZERO,
           HIGH_NOT_PRECEDENCE,IGNORE_SPACE,NO_AUTO_CREATE_USER,
           NO_AUTO_VALUE_ON_ZERO, NO_BACKSLASH_ESCAPES, NO_DIR_IN_CREATE,
           NO_ENGINE_SUBSTITUTION, NO_FIELD_OPTIONS,NO_KEY_OPTIONS,NO_TABLE_OPTIONS, 
           NO_UNSIGNED_SUBTRACTION,NO_ZERO_DATE, NO_ZERO_IN_DATE,
           ONLY_FULL_GROUP_BY, PAD_CHAR_TO_FULL_LENGTH (5.1.20), PIPES_AS_CONCAT,
           REAL_AS_FLOAT, STRICT_ALL_TABLES, STRICT_TRANS_TABLES