各种查资料，最后发现也不是代码问题。
Unable to resolve table ‘XXX’
Unable to resolve column ‘XXX’
表名，和字段解析不到~T喵的，耗费了两天时间

解决方案
解决方案：

参照网页https://mybatis.org/mybatis-3/zh/getting-started.html

首先新建一个项目

项目结构大概

 数据库可以参考代码自己写

一. 配置好pom.xml文件

<!--MyBasit-->
<dependency>
  <groupId>org.mybatis</groupId>
  <artifactId>mybatis</artifactId>
  <version>3.4.6</version>
</dependency>
<!--mysql-->
<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
  <version>8.0.15</version>
</dependency>

二 .新建resources包

新建jdbc.properties文件

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/eend?useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
username=root
password=123456
initialSize=5
minIdle=5
maxActive=20
maxWait=3000
#注释的 是oracle数据库配置
#driver=oracle.jdbc.OracleDriver
#url=jdbc:oracle:thin:@localhost:1521:orcl
#username=system
#password=123456
#initialSize=5
#minIdle=5
#maxActive=20
#maxWait=3000

三 .新建一个entity包,我的少打了一个字母,新建一个userEntiywen的java类

package com.My.Entiy;

public class userEntiy {
    public String id,userName,passWord,img,SJH;

    //生成构造方法
    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassWord() {
        return passWord;
    }

    public void setPassWord(String passWord) {
        this.passWord = passWord;
    }

    public String getImg() {
        return img;
    }

    public void setImg(String img) {
        this.img = img;
    }

    public String getSJH() {
        return SJH;
    }

    public void setSJH(String SJH) {
        this.SJH = SJH;
    }

    @Override
    public String toString() {
        return "userEntiy{" +
                "id='" + id + '\'' +
                ", userName='" + userName + '\'' +
                ", passWord='" + passWord + '\'' +
                ", img='" + img + '\'' +
                ", SJH='" + SJH + '\'' +
                '}';
    }
}

四 . 新建一个Dao包 新建一个userDao的java类

package com.My.Dao;

import com.My.Entiy.userEntiy;

import java.security.PublicKey;
import java.util.List;

public interface userDao {

    public List getList();

    public userEntiy getOne(int id);

    public int del(int id);
}

五 . 在resources包下面新建一个MyBatis.xml文件

<?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>
    <!--    数据库信息  取外部文件-->
    <properties resource="jdbc.properties" />
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mapper/usermapper.xml"/>
    </mappers>
</configuration>

五 . 在resources包下面新建一个mapper包,新建文件usermapper.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.My.Dao.userDao">

    <select id="getList" resultType="com.My.Entiy.userEntiy">
        select * from user
    </select>

    <select id="getOne" resultType="com.My.Entiy.userEntiy">
        select * from user where  id=#{id};
    </select>

    <delete id="del">
        delete from user
        where  id=#{id};
    </delete>
</mapper>

六 . 写一个测试类hello.java删除了id为7的用户

import com.My.Dao.userDao;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;

import java.io.IOException;
import java.io.InputStream;

public class hello {
    @Test
    public void name() throws IOException {
        String resource = "MyBatis.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session=factory.openSession();
        userDao dao=session.getMapper(userDao.class);
//        List list=dao.getList();
//        ProjectEntiy pro=dao.getOne(2);
        int n=dao.del(7);
        System.out.println(n);

        session.commit();
        session.close();
    }
}

七 .注意的点,红色的地方路径必须写对,要和自己的路径对应,get,set方法是点出来的,数据类型和数据库的对应

问题背景：
用idea自带的工具连接数据库，执行查询语句时可以执行成功，但是表名、字段名显示红色

解决方案：
1、勾选下图功能

2、执行刷新