Mybatis-plus多表关联查询，多表分页查询

学习plus真的觉得写代码真的越来越舒服了。昨天开始接触吧，只要学会了多表关联查询。plus就能随意搭配使用了。

关于怎么搭建的就自行了去研究了哦。这里直接进入主题。

我用的是springboot+mybatis-plus。新项目我打算以后都是这样了。

配置一个分页插件！

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Profile;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.plugins.PerformanceInterceptor;

@EnableTransactionManagement
@Configuration
@MapperScan("com.szpdc.Dao")//输入你的dao层的包
public class MybatisPlusConfig {

	/**
	 * 分页插件
	 */
	@Bean
	public PaginationInterceptor paginationInterceptor() {
		return new PaginationInterceptor();
	}

	/**
	 * SQL执行效率插件
	 */
	@Bean
//	@Profile({ "dev", "test" }) // 设置 dev test 环境开启
	public PerformanceInterceptor performanceInterceptor() {
		return new PerformanceInterceptor();
	}
}

Controller

	@RequestMapping("syscal")
	public Object syscal() {

		Page<Map<String, Object>> page=userService.selectListPage(1, 2);

		return page.getRecords();

	}

Service

import java.util.Map;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;

public interface UserService {

	Page<Map<String,Object>> selectListPage(int current, int number);

}

　　

ServiceImpl

import java.util.List;
import java.util.Map;
import org.springframework.stereotype.Service;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;

/**
 *
 * @Author By Yirs
 * @Date 2018-12-01 21:18:06
 * @Description mybatis-plus 在服务层继承了ServiceImpl 就有了 UserMapper的 就少了以前的@Autowired 注入dao层
 */

@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {

	@Override
	public Page<Map<String,Object>> selectListPage(int current, int number) {

		// 新建分页
		Page<Map<String,Object>> page = new Page<Map<String,Object>>(current, number);

		// 返回分页结果 1为id
		return page.setRecords(this.baseMapper.dyGetUserList(page,1));

	}

}

Dao

import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.Select;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;

/**
 *
 *@Author By Yirs
 *@Date 2018-12-01 22:27:13
 */

public interface UserMapper extends BaseMapper<User> {

	/**
	 * 为了区别plus原来的查询select*的字段 ，自定义为dy
	 * @param 分页查询
	 * @return 多表关联查询
	 */
	@Select("SELECT a.id,a.`name`,a.age,b.`describe` FROM USER a LEFT JOIN userinfo b ON a.id = b.user_id where a.id=#{id}")
	List<Map<String, Object>> dyGetUserList(Page<Map<String,Object>> page,Integer id);

}

结果

　　

Sql语句

需要就拿去当测试。

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) CHARACTER SET utf8 DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  `email` varchar(255) CHARACTER SET utf8 DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES ('1', '谢谢', '18', '32as1d564@qq.com');
INSERT INTO `user` VALUES ('2', '行政村v', '22', '3234564@qq.com');
INSERT INTO `user` VALUES ('3', '查询啊', '60', '35asd564@qq.com');
INSERT INTO `user` VALUES ('4', '才表报错', '30', '32弟媳妇64@qq.com');
INSERT INTO `user` VALUES ('5', 'asdasd', '22', 'sdfsad');
INSERT INTO `user` VALUES ('6', 'dsfds', '32', 'sdafsdf');
INSERT INTO `user` VALUES ('7', 'sdfxczv', '33', 'xcvbvchrwt');
INSERT INTO `user` VALUES ('8', 'dfsalkcxjv', '99', 'jklsdhcfvlkjsda');
INSERT INTO `user` VALUES ('9', 'jskdchvc,m', '34', 'dvclkjh');
-- ------------------------------ ------------------------------ ----------------------------
DROP TABLE IF EXISTS `userinfo`;
CREATE TABLE `userinfo` (
  `id` int(11) NOT NULL,
  `user_id` int(11) DEFAULT NULL,
  `describe` varchar(255) CHARACTER SET utf8 DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of userinfo
-- ----------------------------
INSERT INTO `userinfo` VALUES ('1', '1', '用户1');

只要mybatis基础够好这个很好理解的