Mybatis SQL的两种映射方式

1、XML映射文件

1.1、mapper

public interface EmpMapper {
   Emp queryByEmpNo(String empno);
}

1.2、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="org.silence.spring.springbootdemo.mapper.EmpMapper">
    <select id="queryByEmpNo" resultType="Emp" >
        select * from EMP where EMPNO = #{empno}
    </select>
</mapper>

1.3、test

@Test
void queryByEmpNo() {
    Emp emp = mapper.queryByEmpNo("7499");
    System.out.println(emp);
}

2、注解（不需要xml文件）

2.1、mapper

public interface DeptMapper {
    @Select("select * from dept")
    List<Dept> queryAll();

    @Select("select * from dept where deptno = #{deptno}")
    Dept queryByDeptno(String deptno);
}

2.2、test

@Test
void queryByDeptno() {
    Dept dept = mapper.queryByDeptno("20");
    System.out.println(dept);
}