Mybatis处理关联关系

新建个项目

 

 引入依赖有 Spring Boot DevTools ,lombok ,Spring web ,Spring Data JDBC,Mysql Driver,MyBatis Framework

        

 pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>org.example</groupId>
    <artifactId>mybatis-incidence-relation</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
<!--        <dependency>-->
<!--            <groupId>com.baomidou</groupId>-->
<!--            <artifactId>mybatis-plus-boot-starter</artifactId>-->
<!--            <version>3.4.2</version>-->
<!--        </dependency>-->
                <dependency>
                    <groupId>org.mybatis.spring.boot</groupId>
                    <artifactId>mybatis-spring-boot-starter</artifactId>
                    <version>3.0.0</version>
                </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

application.properties

#热部署生效
spring.devtools.restart.enabled=true
#设置重启目录
spring.devtools.restart.additional-paths=src/main/java
#排除目录
spring.devtools.restart.exclude=static/**

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/mydbabc?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true
spring.datasource.username=root
spring.datasource.password=123456



#Mybatis-plus配置
#指定实体包名  单用BaseMapper里方法,不配也行
#mybatis-plus.type-aliases-package=com.example.plusbasemapper.pojo
##指定.xml路径
#mybatis-plus.mapper-locations=classpath:/mapper/*.xml
##开启驼峰命名   可以不配  具体版本
#mybatis-plus.configuration.map-underscore-to-camel-case=true
#mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl



#mybatis配置
mybatis.mapper-locations=classpath:/mapper/*.xml
#配置模型路径
mybatis.type-aliases-package=org.example.mybatisincidencerelation.pojo
#开启驼峰命名
mybatis.configuration.map-underscore-to-camel-case=true


#Spring 框架自带的日志框架(Spring Framework Logging)
logging.level.org.example.mybatisincidencerelation=debug



#http://localhost:8080/actuator/health
#management.endpoint.health.show-details=always

启动看能否正常运行

 新建张表

 

 

一对一关系

 

 用.XML  一对一两种映射关系

 

一般都是做条件查询

 

 

 

一对多关系

比如对应用户有多个订单

 

 

 

 多对一关系其实和1对多关系一样  表还是用上面的表  没啥.....那啥啥啥

 

 多对多关系

 

 

 

 

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转载自blog.csdn.net/tiantiantbtb/article/details/129573090