情形：两个表，cms_mode是主表，cms_model_field是子表，cms_model_field的model_id字段关联到cms_model的主键。
#
# Source for table cms_model
# DROP TABLE IF EXISTS `cms_model`;
CREATE TABLE `cms_model` (
`model_id` int(11) NOT NULL,
`name` varchar(50) NOT NULL DEFAULT '',
`title` varchar(100) NOT NULL DEFAULT '' COMMENT '名称',
) ENGINE=MyISAM DEFAULT CHARSET=utf8 ROW_FORMAT=COMPACT COMMENT='CMS模型表'; #
# Source for table cms_model_field
# DROP TABLE IF EXISTS `cms_model_field`;
CREATE TABLE `cms_model_field` (
`field_id` int(11) NOT NULL AUTO_INCREMENT,
`model_id` int(11) NOT NULL DEFAULT '' COMMENT '模型ID',
`name` varchar(50) DEFAULT NULL COMMENT '名称',
`title` varchar(250) NOT NULL DEFAULT '' COMMENT '标题',
`priority` int(11) NOT NULL DEFAULT '' COMMENT '权重',
`data_type` char(1) NOT NULL DEFAULT '' COMMENT '数据类型(S-字符,N-数值,D-日期,T-备注)',
`is_reserved` tinyint(1) NOT NULL DEFAULT '' COMMENT '是否保留',
PRIMARY KEY (`field_id`)
) ENGINE=MyISAM AUTO_INCREMENT=4 DEFAULT CHARSET=utf8 COMMENT='CMS模型字段表';;
CmsModel.java：
@Entity
@Table(name = "cms_model")
@SuppressWarnings("serial")
public class CmsModel implements Serializable
{
@Id
@GeneratedValue
@Column(name = "model_id")
private Integer id; @Column(name = "name")
private String name; @Column(name = "title")
private String title; @OneToMany(mappedBy = "model",
fetch = FetchType.LAZY)
private List<CmsModelField> fieldList;
}
CmsModelField.java：
@Entity
@Table(name = "cms_model_field")
@SuppressWarnings("serial")
public class CmsModelField implements Serializable
{
@Id
@GeneratedValue
@Column(name = "field_id")
private Integer id; @Column(name = "name")
private String name; @Column(name = "title")
private String title; @Column(name = "data_type")
private String dataType; @Column(name = "priority")
private Integer priority; @Column(name = "is_reserved")
private Boolean reserved; @ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "model_id")
private CmsModel model;
}
@OneToMany Default: FetchType.LAZY默认是延迟抓取，不需要左联接。如果是FetchType.EAGER即时抓取，就会是左联接查询。
@ManyToOne Default: FetchType.EAGER默认是即时抓取，做连接。如果fetch=FetchType.LAZY不是左联接，在需要One的时候直接select。