首页 > 代码库 > Mybatis 级联查询 （一对多 ）
Mybatis 级联查询 （一对多 ）
后台系统中 涉及到添加试卷 问题 答案的一个模块的。我需要通过试卷 查询出所有的试题，以及试题的答案。这个主要要使用到Mybatis的级联查询。
通过试卷 查询出与该试卷相关的试题(一对多)，查询出试题的答案及分数（一对多）。
SelfTestTitle 实体类，SelfTestQuestion实体类，SelfTestAnswer实体类。
package org.system.entity.self;import java.util.List;import org.core.entity.BaseEntity;public class SelfTestTitle extends BaseEntity { private Integer id; private String name; private String desc; private String picUrl; private List<SelfTestQuestion> questionList; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getDesc() { return desc; } public void setDesc(String desc) { this.desc = desc; } public String getPicUrl() { return picUrl; } public void setPicUrl(String picUrl) { this.picUrl = picUrl; } public List<SelfTestQuestion> getQuestionList() { return questionList; } public void setQuestionList(List<SelfTestQuestion> questionList) { this.questionList = questionList; } @Override public Integer getPage() { return super.getPage(); } @Override public Integer getRows() { return super.getRows(); }}
package org.system.entity.self;import java.util.List;import javax.validation.constraints.NotNull;import org.core.entity.BaseEntity;import org.hibernate.validator.constraints.NotBlank;import org.utils.spring.Groups;public class SelfTestQuestion extends BaseEntity { private Integer id; @NotNull(message = "{selfTestTitle.id.notnull.valid}", groups = { Groups.Insert.class }) private Integer titleId; @NotBlank(message = "{question.notblank.valid}", groups = { Groups.Insert.class }) private String question; @NotNull(message = "{viewOrder.notnull.valid}", groups = { Groups.Insert.class }) private Integer viewOrder; private List<SelfTestAnswer> answersList; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public Integer getTitleId() { return titleId; } public void setTitleId(Integer titleId) { this.titleId = titleId; } public String getQuestion() { return question; } public void setQuestion(String question) { this.question = question; } public Integer getViewOrder() { return viewOrder; } public void setViewOrder(Integer viewOrder) { this.viewOrder = viewOrder; } public List<SelfTestAnswer> getAnswersList() { return answersList; } public void setAnswersList(List<SelfTestAnswer> answersList) { this.answersList = answersList; } @Override public Integer getPage() { return super.getPage(); } @Override public Integer getRows() { return super.getRows(); }}
package org.system.entity.self;import org.core.entity.BaseEntity;public class SelfTestAnswer extends BaseEntity { private Integer id; private Integer questionId; private String answer; private Integer score; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public Integer getQuestionId() { return questionId; } public void setQuestionId(Integer questionId) { this.questionId = questionId; } public String getAnswer() { return answer; } public void setAnswer(String answer) { this.answer = answer; } public Integer getScore() { return score; } public void setScore(Integer score) { this.score = score; } @Override public Integer getPage() { return super.getPage(); } @Override public Integer getRows() { return super.getRows(); }}
1 <!-- 查询试卷详情 --> 2 <select id="queryOne" parameterType="org.system.entity.self.SelfTestTitle" resultMap="getSelfTestQuestionMap"> 3 select id, name, `desc` de, pic_url picUrl 4 from self_test_title 5 where id = #{id} 6 </select> 7 <!-- 定义结果集 试卷下的问题 --> 8 <resultMap type="map" id="getSelfTestQuestionMap"> 9 <result property="id" column="id" />10 <collection property="questionList" column="id" javaType="list" select="getSelfTestQuestions"/>11 </resultMap>12 13 <!-- 查询问题 -->14 <select id="getSelfTestQuestions" parameterType="org.system.entity.self.SelfTestTitle" resultMap="getSelfTestAnswersMap">15 select id, title_id titleId, question, view_order viewOrder16 from self_test_question17 where title_id = #{id}18 </select> 19 20 <!-- 定义结果集 问题下的答案 -->21 <resultMap type="map" id="getSelfTestAnswersMap">22 <result property="id" column="id"/>23 <collection property="answersList" column="id" javaType="list" select="getSelfTestAnswers"></collection>24 </resultMap>25 <!-- 查询问题 -->26 <select id="getSelfTestAnswers" parameterType="org.system.entity.self.SelfTestAnswer" resultType="map">27 select id ,question_id questionId,answer ,score from self_test_answer where question_id =#{id}28 </select>
property：属性名称
column：外键列
javaType：类型（可以是自己的实体类）
select：关联的查询语句
collection：一对多的标签
property：属性名称
column：外键列
查询出来的结果
现在主要是要让他显示出来了！
Mybatis 级联查询 （一对多 ）
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