在MyBatis中使用XML进行多表查询、子查询和连接查询的技巧：深入了解mybatis-config.xml中的数据源和日志配置

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!--    dddd-->
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="ture"/><!--配置下划线转换为驼峰命名风格-->
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"></transactionManager><!--事务管理器-->
            <dataSource type="POOLED"><!--数据源 POOLED代表池化-->
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="dao/StudentDao.xml"></mapper>
        <mapper resource="dao/TypeDao.xml"></mapper>
    </mappers>
</configuration>