##创建视图

CREATE VIEW 视图名 as 要多表联查的sql语句

##移除视图

DROP VIEW 视图名

##创建视图
CREATE VIEW view_test AS SELECT u.*,r.role_name,r.role_id FROM USER u,role r,user_role ur WHERE u.user_id = ur.user_id AND r.role_id = ur.role_id

##查询视图
SELECT * FROM view_test WHERE role_id =2

##更新操作表
update 视图名 set 字段名 = 字段值

package com.yblue.mapper;

import com.yblue.domain.Role;
import com.yblue.domain.User;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

import java.util.List;

/**
 * @author: JiaXinMa
 * @description: Role Dao层
 * @date: 2021/3/26
 */
public interface RoleMapper extends BaseMapper<Role> {

   @Select("SELECT * FROM view_test where role_id=#{roleId}")
    List<User> getViewTest(@Param("roleId") Integer roleId);
}

package com.yblue.domain;


import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

/**
 * @author: JiaXinMa
 * @description: 用户实体类
 * @date: 2021/3/26
 */
@Data
@TableName("user")
public class User extends Role{

    @TableId(type = IdType.AUTO)//自增主键
    @TableField("user_id")
    private Integer userId;//用户Id

    @TableField("user_code")
    private String userCode;//用户编号

    private String name;//用户姓名

    private String username;//用户账号

    private String password;//用户密码

    @TableField("organization_id")
    private Integer organizationId;//部门Id

    private Integer status;//状态:0停用/1启用

    private String telephone;//手机号码

    private String remark;//备注
}

package com.yblue.test;

import com.yblue.domain.User;
import com.yblue.mapper.RoleMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

/**
 * @author JiaXinMa
 * @description 测试视图
 * @date 2021/5/14
 */
@SpringBootTest
public class TestSQLView {

    @Autowired
    RoleMapper roleMapper;

    @Test
    public void getViewTest() {
        List<User> users = roleMapper.getViewTest(2);
        System.out.println("输出:"+users);
    }
}