现有员工表employee，字段id，name，age，position。要求：在数据库建立该表，并插入初始数据。 使用Mybatis完成一下几个功能： （1）根据id查询员工信息 （2）新增员工信息 （3）根据id修改员工信息 （4）根据id删除员工信息

在MyBatis中，首先需要创建对应的XML映射文件，以及Java配置文件来进行持久层的操作。以下是四个功能的具体步骤：

1. 创建EmployeeMapper.xml映射文件：

<?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.example.mapper.EmployeeMapper">

    <!-- 根据id查询员工 -->
    <select id="getEmployeeById" parameterType="int" resultType="com.example.entity.Employee">
        SELECT * FROM employee WHERE id = #{id}
    </select>

    <!-- 新增员工 -->
    <insert id="addEmployee" parameterType="com.example.entity.Employee">
        INSERT INTO employee (id, name, age, position)
        VALUES (#{id}, #{name}, #{age}, #{position})
    </insert>

    <!-- 修改员工信息 -->
    <update id="updateEmployeeById" parameterType="com.example.entity.Employee">
        UPDATE employee SET name = #{name}, age = #{age}, position = #{position} WHERE id = #{id}
    </update>

    <!-- 删除员工信息 -->
    <delete id="deleteEmployeeById" parameterType="int">
        DELETE FROM employee WHERE id = #{id}
    </delete>
</mapper>

2. 在Java配置中注册这个Mapper并提供DAO接口：

package com.example.mapper;

import com.example.entity.Employee;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Update;
import org.apache.ibatis.annotations.Delete;

public interface EmployeeMapper {
    @Select("SELECT * FROM employee WHERE id = #{id}")
    Employee getEmployeeById(int id);

    @Insert("INSERT INTO employee (id, name, age, position) VALUES (#{id}, #{name}, #{age}, #{position})")
    void addEmployee(Employee employee);

    @Update("UPDATE employee SET name = #{name}, age = #{age}, position = #{position} WHERE id = #{id}")
    void updateEmployeeById(Employee employee);

    @Delete("DELETE FROM employee WHERE id = #{id}")
    void deleteEmployeeById(int id);
}