CREATE TABLE `dept_emp` (
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`emp_no` int(11) NOT NULL,
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`dept_no` char(4) NOT NULL,
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`from_date` date NOT NULL,
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`to_date` date NOT NULL,
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PRIMARY KEY (`dept_no`,`emp_no`),
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KEY `ix_fromdate` (`from_date`),
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KEY `ix_empno_fromdate` (`emp_no`,`from_date`)
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) ENGINE=InnoDB DEFAULT CHARSET=utf8;
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mysql> explain select * from dept_emp where (emp_no, dept_no) in ( (10017,'d001'), (10208, 'd001'));
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+----+-------------+----------+------+---------------+------+---------+------+--------+-------------+
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| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
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+----+-------------+----------+------+---------------+------+---------+------+--------+-------------+
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| 1 | SIMPLE | dept_emp | ALL | NULL | NULL | NULL | NULL | 331143 | Using where |
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+----+-------------+----------+------+---------------+------+---------+------+--------+-------------+
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1 row in set (0.00 sec)
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mysql> select version();
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+------------+
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| version() |
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+------------+
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| 5.6.15-log |
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+------------+
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1 row in set (0.00 sec)
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