Hibernate 关联映射之多对一
Hibernate的关联映射包括：
一对一（Persion - IDCard）
一对多（Department - Employee）
多对一（Employee - Department）
多对多（Teacher - Student）
组件映射（User - Name）
集合映射（Set、List、Map）
inverse和cascade（Employee - Department）
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本文以多对一为例：
多个员工对应一个部门（Employee - Department）
映射文件 <many-to-one name="depart" column="depart_id">
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实体类：Department.java 和 Employee.java
CREATE TABLE `department` ( `id` int(11) NOT NULL auto_increment, `name` varchar(255) default NULL, PRIMARY KEY (`id`)) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=latin1CREATE TABLE `employee` ( `id` int(11) NOT NULL auto_increment, `name` varchar(255) default NULL, `dept` int(11) default NULL, PRIMARY KEY (`id`), KEY `FK4AFD4ACE66A70F4E` (`dept`), CONSTRAINT `FK4AFD4ACE66A70F4E` FOREIGN KEY (`dept`) REFERENCES `department` (`id`)) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=latin1
mysql> desc department;
+-------+--------------+------+-----+---------+----------------+
| Field | Type???????? | Null | Key | Default | Extra????????? |
+-------+--------------+------+-----+---------+----------------+
| id??? | int(11)????? | NO?? | PRI | NULL??? | auto_increment |
| name? | varchar(255) | YES? |???? | NULL??? |??????????????? |
+-------+--------------+------+-----+---------+----------------+
mysql> desc employee;
+-------+--------------+------+-----+---------+----------------+
| Field | Type???????? | Null | Key | Default | Extra????????? |
+-------+--------------+------+-----+---------+----------------+
| id??? | int(11)????? | NO?? | PRI | NULL??? | auto_increment |
| name? | varchar(255) | YES? |???? | NULL??? |??????????????? |
| dept? | int(11)????? | YES? | MUL | NULL??? |??????????????? |
+-------+--------------+------+-----+---------+----------------+
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