【MyBatis】XML版快速入门——练习题

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陶然同学 2023-05-06 00:59:54 ©著作权

文章标签 mybatis xml java ci mysql 文章分类 Python 后端开发

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1、准备工作

1.1、导入依赖（mybatis启动器和mysql驱动）

1.2.、yml中配置MyBatis的配置

3、编写domain、mapper、xml

2、数据库准备

2.1、类型表

2.2、老师表

2.3、班级表

2.4、城市表

2.5、学生表

2.6、课程表

2.7、中间表

3、练习题

3.1、练习1

3.2、练习2

3.3、练习3

3.4、练习4

3.5、练习5

3.6、优化

4、总结

1、准备工作

1.1、导入依赖（mybatis启动器和mysql驱动）

<!-- mybatis启动器 -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>

        <!-- mysql驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
        </dependency>

1.2.、yml中配置MyBatis的配置

server:
  port: 8888
spring:
  application:
    name: tanhua-test-xml
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/test2?useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true&useSSL=false
    username: root
    password: 123456
mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.czxy.domain
  configuration:
    map-underscore-to-camel-case: true
logging:
  level:
    com.czxy.mapper: debug

【MyBatis】XML版快速入门——练习题_mybatis

3、编写domain、mapper、xml

【MyBatis】XML版快速入门——练习题_xml_02

@Mapper作用与 Mapper 用于告诉sprigng框架此接口的实现类由Mybatis负责创建，并将其实现类对象存储到spring容器中。

【MyBatis】XML版快速入门——练习题_xml_03

编写xml namespace对应你的mapper

2、数据库准备

2.1、类型表

CREATE TABLE `tb_teacher_type` (
  `type_id` INT(11) NOT NULL PRIMARY KEY AUTO_INCREMENT,
  `content` VARCHAR(50) COMMENT '类型'
);

INSERT  INTO `tb_teacher_type`(`type_id`,`content`) VALUES (1,'授课老师');
INSERT  INTO `tb_teacher_type`(`type_id`,`content`) VALUES (2,'助理老师');
INSERT  INTO `tb_teacher_type`(`type_id`,`content`) VALUES (3,'辅导员老师');

2.2、老师表

CREATE TABLE `tb_teacher` (
  `tid` INT(11) NOT NULL PRIMARY KEY AUTO_INCREMENT,
  `tname` VARCHAR(50) DEFAULT NULL COMMENT '老师姓名',
  `type` INT(11) DEFAULT NULL COMMENT '老师类型ID'
);
INSERT  INTO `tb_teacher`(`tid`,`tname`,`type`) VALUES (1,'梁桐老师',1);
INSERT  INTO `tb_teacher`(`tid`,`tname`,`type`) VALUES (2,'马坤老师',2);
INSERT  INTO `tb_teacher`(`tid`,`tname`,`type`) VALUES (3,'仲燕老师',3);
INSERT  INTO `tb_teacher`(`tid`,`tname`,`type`) VALUES (4,'袁新奇老师',1);
INSERT  INTO `tb_teacher`(`tid`,`tname`,`type`) VALUES (5,'任林达老师',2);
INSERT  INTO `tb_teacher`(`tid`,`tname`,`type`) VALUES (6,'王珊珊老师',3);

2.3、班级表

CREATE TABLE `tb_class` (
  `cid` INT(11) NOT NULL PRIMARY KEY AUTO_INCREMENT,
  `cname` VARCHAR(50) DEFAULT NULL COMMENT '班级名称',
  `teacher1_id` INT(11) DEFAULT NULL COMMENT '授课老师',
  `teacher2_id` INT(11) DEFAULT NULL COMMENT '助理老师',
  `teacher3_id` INT(11) DEFAULT NULL COMMENT '辅导员老师'
);

INSERT  INTO `tb_class`(`cid`,`cname`,`teacher1_id`,`teacher2_id`,`teacher3_id`) VALUES (1,'Java56',1,2,3);
INSERT  INTO `tb_class`(`cid`,`cname`,`teacher1_id`,`teacher2_id`,`teacher3_id`) VALUES (2,'Java78',1,2,3);
INSERT  INTO `tb_class`(`cid`,`cname`,`teacher1_id`,`teacher2_id`,`teacher3_id`) VALUES (3,'Java12',4,5,6);
INSERT  INTO `tb_class`(`cid`,`cname`,`teacher1_id`,`teacher2_id`,`teacher3_id`) VALUES (4,'Java34',4,5,6);

2.4、城市表

CREATE TABLE tb_city(
  c_id VARCHAR(32) PRIMARY KEY COMMENT '城市ID',
  city_name VARCHAR(20) COMMENT '城市名称' ,
  parent_id VARCHAR(32) COMMENT '父ID'
);

INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('320000','江苏省','0');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('140000','山西省','0');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('130000','河北省','0');

INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('320100','南京市','320000');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('320102','玄武区','320100');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('320103','白下区','320100');

INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('321300','宿迁市','320000');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('321322','沭阳县','321300');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('321323','泗阳县','321300');


INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('140100','太原市','140000');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('140106','迎泽区','140100');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('140108','尖草坪区','140100');

INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('140800','运城市','140000');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('140823','闻喜县','140800');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('140828','夏　县','140800');

INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('130100','石家庄市','130000');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('130127','高邑县','130100');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('130185','鹿泉市','130100');

INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('131000','廊坊市','130000');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('131003','广阳区','131000');
INSERT INTO tb_city(c_id,city_name,parent_id) VALUES('131022','固安县','131000');

2.5、学生表

CREATE TABLE `tb_student` (
  `s_id` INT NOT NULL PRIMARY KEY AUTO_INCREMENT COMMENT '学生ID',
  `sname` VARCHAR(50) DEFAULT NULL COMMENT '姓名',
  `age` INT(11) DEFAULT NULL COMMENT '年龄',
  `birthday` DATETIME DEFAULT NULL COMMENT '生日',
  `gender` CHAR(1) DEFAULT NULL COMMENT '性别',
  `c_id` INT DEFAULT NULL COMMENT '班级ID',
  `province_id` VARCHAR(32) DEFAULT NULL COMMENT '省ID',
  `city_id` VARCHAR(32) DEFAULT NULL COMMENT '市ID',
  `county_id` VARCHAR(32) DEFAULT NULL COMMENT '县ID'
);

INSERT  INTO `tb_student`(`s_id`,`sname`,`age`,`birthday`,`gender`,`c_id`,`province_id`,`city_id`,`county_id`) VALUES (1,'赵三33',21,'2001-01-17 00:00:00','1',1,'320000','321300','321322');
INSERT  INTO `tb_student`(`s_id`,`sname`,`age`,`birthday`,`gender`,`c_id`,`province_id`,`city_id`,`county_id`) VALUES (2,'钱四444',1900,'2001-05-16 00:00:00','1',2,'320000','321300','321322');
INSERT  INTO `tb_student`(`s_id`,`sname`,`age`,`birthday`,`gender`,`c_id`,`province_id`,`city_id`,`county_id`) VALUES (3,'孙五56',189,'2022-03-15 00:00:00','0',1,'320000','321300','321322');
INSERT  INTO `tb_student`(`s_id`,`sname`,`age`,`birthday`,`gender`,`c_id`,`province_id`,`city_id`,`county_id`) VALUES (4,'张三',20,'2020-12-21 00:00:00','0',2,'320000','321300','321322');
INSERT  INTO `tb_student`(`s_id`,`sname`,`age`,`birthday`,`gender`,`c_id`,`province_id`,`city_id`,`county_id`) VALUES (5,'xxx',18,'2020-12-21 00:00:00','0',2,'140000','140800','140823');
INSERT  INTO `tb_student`(`s_id`,`sname`,`age`,`birthday`,`gender`,`c_id`,`province_id`,`city_id`,`county_id`) VALUES (6,'123',18,'2020-11-01 00:00:00','0',3,'130000','130100','130127');
INSERT  INTO `tb_student`(`s_id`,`sname`,`age`,`birthday`,`gender`,`c_id`,`province_id`,`city_id`,`county_id`) VALUES (7,'xx',18,'2020-11-02 00:00:00','0',1,'130000','131000','131003');

2.6、课程表

CREATE TABLE `tb_course` (
  `c_id` INT NOT NULL PRIMARY KEY COMMENT '课程ID',
  `cname` VARCHAR(50) DEFAULT NULL COMMENT '课程名称',
  `desc` VARCHAR(100) DEFAULT NULL COMMENT '课程描述'
);

INSERT  INTO `tb_course`(`c_id`,`cname`,`desc`) VALUES (1,'Java基础','JavaSE所有课程');
INSERT  INTO `tb_course`(`c_id`,`cname`,`desc`) VALUES (2,'JavaWeb','Java Web 所有课程');
INSERT  INTO `tb_course`(`c_id`,`cname`,`desc`) VALUES (3,'SSM','Spring Mvc、Spring、MyBatis所有课程');

2.7、中间表

CREATE TABLE `tb_student_course` (
  `s_id` INT NOT NULL COMMENT '学生ID',
  `c_id` INT NOT NULL COMMENT '课程ID',
  `score` DOUBLE DEFAULT NULL,
  PRIMARY KEY (`s_id`,`c_id`)
);

INSERT INTO tb_student_course(s_id,c_id,score) VALUES(1,1,100);
INSERT INTO tb_student_course(s_id,c_id,score) VALUES(1,2,95);
INSERT INTO tb_student_course(s_id,c_id,score) VALUES(1,3,NULL);

INSERT INTO tb_student_course(s_id,c_id,score) VALUES(2,1,100);
INSERT INTO tb_student_course(s_id,c_id,score) VALUES(2,2,95);
INSERT INTO tb_student_course(s_id,c_id,score) VALUES(2,3,100);

INSERT INTO tb_student_course(s_id,c_id,score) VALUES(3,1,80);
INSERT INTO tb_student_course(s_id,c_id,score) VALUES(3,2,NULL);
INSERT INTO tb_student_course(s_id,c_id,score) VALUES(3,3,90);

3、练习题

3.1、练习1

查询所有的老师，同时

查询老师对应的类型
查询老师所教授的课程

TeacherMapper：

@Mapper
public interface TeacherMapper {
    /**
     * 查询所有
     * @return
     */
    List<Teacher> selectAll();

}

TeacherMapper.xml

<?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.czxy.mapper.TeacherMapper">

    <resultMap id="teacherResultMap" type="teacher">
        <result property="type" column="type"></result>
        <result property="tid" column="tid"></result>

        <association property="teacherType" column="type" select="com.czxy.mapper.TeacherTypeMapper.selectById"></association>

        <collection property="courseList" column="tid" select="com.czxy.mapper.CourseMapper.selectCourseIdTeacher"></collection>
    </resultMap>


    <select id="selectAll" resultMap="teacherResultMap">
        select * from tb_teacher
    </select>


</mapper>

TeacherTypeMapper.xml

<?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.czxy.mapper.TeacherTypeMapper">

    <select id="selectById" resultType="teacherType">
        select * from tb_teacher_type where type_id = #{typeId}
    </select>

</mapper>

CourseMapper.xml

<?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.czxy.mapper.CourseMapper">

    <resultMap id="courseResultMap" type="course">
        <result property = "cid" column = "c_id"></result>

        <association property="total" column="c_id" select="com.czxy.mapper.StudentMapper.countByCourseId"></association>

        <collection property="studentList" column="c_id" select="com.czxy.mapper.StudentMapper.selectAllByCourseId"></collection>
    </resultMap>


    <select id="selectCourseIdTeacher" resultMap="courseResultMap">
        select c.* from tb_course c inner join tb_course_teacher ct on ct.c_id = c.c_id where ct.t_id = #{teacherId}
    </select>

</mapper>

3.2、练习2

查询所有的班级，同时

查询班级对应的老师
查询班级学生的总人数
查询班级包含的学生详情

CourseMapper

@Mapper
public interface CourseMapper {


    public List<Course> selectAll();

}

CourseMapper.xml

<?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.czxy.mapper.CourseMapper">

    <resultMap id="courseResultMap" type="course">
        <result property = "cid" column = "c_id"></result>

        <association property="total" column="c_id" select="com.czxy.mapper.StudentMapper.countByCourseId"></association>

        <collection property="studentList" column="c_id" select="com.czxy.mapper.StudentMapper.selectAllByCourseId"></collection>
    </resultMap>


    <select id="selectAll" resultMap="courseResultMap">
        select * from tb_course
    </select>

</mapper>

StudentMapper.xml

<?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.czxy.mapper.StudentMapper">

    <select id="countByCourseId" resultType="long">
        select count(1) from tb_student s
            inner join tb_student_course sc on s.s_id = sc.s_id
            where sc.c_id = #{courseId}
    </select>

    <select id="selectAllByCourseId" resultType="student">
        select * from tb_student s
            inner join tb_student_course sc on s.s_id = sc.s_id
            where sc.c_id = #{courseId}
    </select>
    
</mapper>

3.3、练习3

查询所有的学生，同时

查询学生所属班级
查询学生省市县信息
查询学生所学课程

StudentMapper

@Mapper
public interface StudentMapper {
   
    /**
     * 查询所有
     * @return
     */
    List<Student> selectAll();
}

StudentMapper.xml

<?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.czxy.mapper.StudentMapper">

    <resultMap id="studentResultMap" type="student">
        <result property="sid" column="s_id"></result>
        <result property="cid" column="c_id"></result>
        <result property="provinceId" column="province_id"></result>
        <result property="cityId" column="city_id"></result>
        <result property="countyId" column="county_id"></result>

        <association property="classes" column="c_id" select="com.czxy.mapper.ClassesMapper.selectById"></association>

        <association property="province" column="province_id" select="com.czxy.mapper.CityMapper.selectById"></association>
        <association property="city" column="city_id" select="com.czxy.mapper.CityMapper.selectById"></association>
        <association property="county" column="county_id" select="com.czxy.mapper.CityMapper.selectById"></association>

        <collection property="courseList" column="s_id" select="com.czxy.mapper.CourseMapper.selectAllByStudentId"></collection>
    </resultMap>

    <select id="selectAll" resultMap="studentResultMap">
        select * from tb_student
    </select>

</mapper>

ClassesMapper.xml

<?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.czxy.mapper.ClassesMapper">

    <select id="selectById" resultType="classes">
        select * from tb_class where cid = #{classesId}
    </select>

</mapper>

CityMapper.xml

<?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.czxy.mapper.CityMapper">

    <select id="selectById" resultType="city">
        select * from tb_city where c_id = #{cid}
    </select>

</mapper>

CourseMapper.xml

<?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.czxy.mapper.CourseMapper">

    <select id="selectAllByStudentId" resultType="course">
        select c.* from tb_course c
        inner join tb_student_course sc on c.c_id = sc.c_id
        where sc.s_id = #{studentId}
    </select>

</mapper>

3.4、练习4

查询所有课程，同时

查询学生学习该课程总人数
查询学生学习该课程详情

CourseMapper

@Mapper
public interface CourseMapper {

    public List<Course> selectAll();
}

CourseMapper.xml

<?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.czxy.mapper.CourseMapper">

    <resultMap id="courseResultMap" type="course">
        <result property = "cid" column = "c_id"></result>

        <association property="total" column="c_id" select="com.czxy.mapper.StudentMapper.countByCourseId"></association>

        <collection property="studentList" column="c_id" select="com.czxy.mapper.StudentMapper.selectAllByCourseId"></collection>
    </resultMap>

    <select id="selectAll" resultMap="courseResultMap">
        select * from tb_course
    </select>

</mapper>

StudentMapper.xml

<?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.czxy.mapper.StudentMapper">

    <select id="countByCourseId" resultType="long">
        select count(1) from tb_student s
            inner join tb_student_course sc on s.s_id = sc.s_id
            where sc.c_id = #{courseId}
    </select>

    <select id="selectAllByCourseId" resultType="student">
        select * from tb_student s
            inner join tb_student_course sc on s.s_id = sc.s_id
            where sc.c_id = #{courseId}
    </select>
    
</mapper>

3.5、练习5

创建或修改表，完成老师与课程关联关系

不同的老师可以教授不同的课程
不同的课程可以由不同的老师教授

3.6、优化

优化：2.1、2.2、2.3、2.4，该查询所有为指定若干

4、总结

@Param作用：给参数命名 sql语句使用#{}或${}取出

mybatis.mapper-locations:classpath:mapper/*.xml：扫描mapper mapper接口与mapper xml

才能绑定

mybatis.type-aliases-package：扫描自定义POJO 映射不用全类名可以直接写类名

mybatis.configuration.map-underscore-to-camel-case：开启自动驼峰命名转换

<ResultMap>

ResultMap：自定义结果集映射规则，自定义某个JavaBean的封装规则。

type：返回的类型

id：指定主键列的封装规则（主键也可以使用result来定义）

property：指定对应的javaBean属性

column：指定哪一列

<association>

association：配置一对一关联

property：指定对应的javaBean属性

column：指定哪一列

select：dao层进行查询的方法

<collection>

collection：一对多关联

property：指定对应的javaBean属性

column：指定哪一列

select：dao层进行查询的方法

select、update、delete的parameterType

传递参数的类型

<foreach>

foeach是mybatis的动态标签一般用来批量操作

collection：传入的集合【必选】

item：集合中元素迭代时的别名【必选】

open：代码开始符号一般时(和close)合用常用in(),values()时【可选】

separator：元素之间的分隔符一般用，【可选】

close：代码关闭符号 ) 【可选】

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