mybatis 一对一、一对多、多对一、多对多

本项目是  框架架构是 springboot+mybatis

添加maven依赖

<dependency>    <groupId>org.mybatis.spring.boot</groupId>    <artifactId>mybatis-spring-boot-starter</artifactId>    <version>${mybatis-spring-boot.version}</version></dependency>

在 application.properties 配置

#为实体对象所在的包，跟数据库表一一对应mybatis.typeAliasesPackage=com.exer.demo.entity#mapper文件的位置mybatis.mapperLocations=classpath:mapper/*.xml



数据库DROP TABLE IF EXISTS `student`;CREATE TABLE `student` (  `id` bigint(30) NOT NULL AUTO_INCREMENT,  `name` varchar(255) DEFAULT NULL,  `age` int(30) DEFAULT NULL,  `teacher_id` bigint(30) DEFAULT NULL,  PRIMARY KEY (`id`)) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

-- ------------------------------ Records of student-- ----------------------------INSERT INTO `student` VALUES (‘1‘, ‘weww‘, ‘10‘, ‘1‘);INSERT INTO `student` VALUES (‘2‘, ‘asdd‘, ‘12‘, ‘1‘);

-- ------------------------------ Table structure for teacher-- ----------------------------DROP TABLE IF EXISTS `teacher`;CREATE TABLE `teacher` (  `id` bigint(30) NOT NULL AUTO_INCREMENT,  `name` varchar(255) DEFAULT NULL,  `age` int(30) DEFAULT NULL,  PRIMARY KEY (`id`)) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

-- ------------------------------ Records of teacher-- ----------------------------INSERT INTO `teacher` VALUES (‘1‘, ‘tytt‘, ‘32‘);INSERT INTO `teacher` VALUES (‘2‘, ‘ytyty‘, ‘24‘);

-- ------------------------------ Table structure for user-- ----------------------------DROP TABLE IF EXISTS `user`;CREATE TABLE `user` (  `id` int(11) NOT NULL COMMENT ‘主键‘,  `name` varchar(64) NOT NULL COMMENT ‘姓名‘,  `birthday` date DEFAULT NULL COMMENT ‘生日‘,  `address` varchar(256) DEFAULT NULL COMMENT ‘地址‘,  PRIMARY KEY (`id`)) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ------------------------------ Records of user-- ----------------------------INSERT INTO `user` VALUES (‘1‘, ‘小明‘, ‘2017-08-12‘, ‘北京市丰台区科怡路‘);INSERT INTO `user` VALUES (‘2‘, ‘小刚‘, ‘2017-08-12‘, ‘北京市海淀区‘);

-- ------------------------------ Table structure for user_device-- ----------------------------DROP TABLE IF EXISTS `user_device`;CREATE TABLE `user_device` (  `id` int(11) NOT NULL COMMENT ‘主键‘,  `user_device_name` varchar(64) NOT NULL COMMENT ‘设备名称‘,  `user_id` int(11) DEFAULT NULL COMMENT ‘用户ID‘,  PRIMARY KEY (`id`)) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ------------------------------ Records of user_device-- ----------------------------INSERT INTO `user_device` VALUES (‘1‘, ‘安卓‘, ‘1‘);INSERT INTO `user_device` VALUES (‘2‘, ‘IOS‘, ‘1‘);