项目中多表查询

2021-07-23 12:31:57 阅读：196 来源： 互联网

标签：String 项目 private 查询 ApiModelProperty value 中多表 id ec

1,实体类：


/**
 * <p>
 * 课程
 * </p>
 *
 * @author testjava
 * @since 2020-03-02
 */
@Data
@EqualsAndHashCode(callSuper = false)
@Accessors(chain = true)
@ApiModel(value="EduCourse对象", description="课程")
public class EduCourse implements Serializable {

    private static final long serialVersionUID = 1L;

    @ApiModelProperty(value = "课程ID")
    @TableId(value = "id", type = IdType.ID_WORKER_STR)
    private String id;

    @ApiModelProperty(value = "课程讲师ID")
    private String teacherId;

    @ApiModelProperty(value = "二级分类ID")
    private String subjectId;

    @ApiModelProperty(value = "一级分类级ID")
    private String subjectParentId;

    @ApiModelProperty(value = "课程标题")
    private String title;

    @ApiModelProperty(value = "课程销售价格，设置为0则可免费观看")
    private BigDecimal price;

    @ApiModelProperty(value = "总课时")
    private Integer lessonNum;

    @ApiModelProperty(value = "课程封面图片路径")
    private String cover;

    @ApiModelProperty(value = "销售数量")
    private Long buyCount;

    @ApiModelProperty(value = "浏览数量")
    private Long viewCount;

    @ApiModelProperty(value = "乐观锁")
    private Long version;

    @ApiModelProperty(value = "课程状态 Draft未发布  Normal已发布")
    private String status;

    @ApiModelProperty(value = "逻辑删除 1（true）已删除， 0（false）未删除")
    private Integer isDeleted;

    @ApiModelProperty(value = "创建时间")
    @TableField(fill = FieldFill.INSERT)
    private Date gmtCreate;

    @ApiModelProperty(value = "更新时间")
    @TableField(fill = FieldFill.INSERT_UPDATE)
    private Date gmtModified;


}

2.然后创建要查询出信息的vo类

@Data
public class CoursePublishVo {
    private String id;
    private String title;
    private String cover;
    private Integer lessonNum;
    private String subjectLevelOne;
    private String subjectLevelTwo;
    private String teacherName;
    private String price;//只用于显示
}

3.去相对应的Mapper中创建接口

/**
 * <p>
 * 课程 Mapper 接口
 * </p>
 *
 * @author testjava
 * @since 2020-03-02
 */
public interface EduCourseMapper extends BaseMapper<EduCourse> {

    public CoursePublishVo getPublishCourseInfo(String courseId);
}

4.然后再去xml，写sql语句

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.atguigu.eduservice.mapper.EduCourseMapper">
    <!--sql语句：根据课程id查询课程确认信息-->
    <select id="getPublishCourseInfo" resultType="com.atguigu.eduservice.entity.vo.CoursePublishVo">
        SELECT ec.id,ec.title,ec.price,ec.lesson_num AS lessonNum,ec.cover,
               et.name AS teacherName,
               es1.title AS subjectLevelOne,
               es2.title AS subjectLevelTwo
        FROM edu_course ec LEFT OUTER JOIN edu_course_description ecd ON ec.id=ecd.id
                           LEFT OUTER JOIN edu_teacher et ON ec.teacher_id=et.id
                           LEFT OUTER JOIN edu_subject es1 ON ec.subject_parent_id=es1.id
                   LEFT OUTER JOIN edu_subject es2 ON ec.subject_id=es2.id
        WHERE ec.id=#{courseId}
    </select>
</mapper>

5.去Controller里填写路径和调用

    //根据课程id查询课程确认信息
    @GetMapping("getPublishCourseInfo/{id}")
    public R getPublishCourseInfo(@PathVariable String id) {
        CoursePublishVo coursePublishVo = courseService.publishCourseInfo(id);
        return R.ok().data("publishCourse",coursePublishVo);
    }

6.Service填写接口

    //根据课程id查询课程确认信息
    CoursePublishVo publishCourseInfo(String id);

7.最后去Servicelmpl里去调用Mapper

    //根据课程id查询课程确认信息
    @Override
    public CoursePublishVo publishCourseInfo(String id) {
        //调用mapper
        CoursePublishVo publishCourseInfo = baseMapper.getPublishCourseInfo(id);
        return publishCourseInfo;
    }

标签：String,项目,private,查询,ApiModelProperty,value,中多表,id,ec
来源： https://blog.csdn.net/qq_45464015/article/details/119029630

本站声明： 1. iCode9 技术分享网（下文简称本站）提供的所有内容，仅供技术学习、探讨和分享；
2. 关于本站的所有留言、评论、转载及引用，纯属内容发起人的个人观点，与本站观点和立场无关；
3. 关于本站的所有言论和文字，纯属内容发起人的个人观点，与本站观点和立场无关；
4. 本站文章均是网友提供，不完全保证技术分享内容的完整性、准确性、时效性、风险性和版权归属；如您发现该文章侵犯了您的权益，可联系我们第一时间进行删除；
5. 本站为非盈利性的个人网站，所有内容不会用来进行牟利，也不会利用任何形式的广告来间接获益，纯粹是为了广大技术爱好者提供技术内容和技术思想的分享性交流网站。

ICode9

项目中多表查询