mybaties plus插入数据，自动回显 机制

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结论：mybaties plus会将库里数据自动回显到 要插入的数据上

测试表格

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;-- 表结构
DROP TABLE IF EXISTS `t_stu`;
CREATE TABLE `t_stu`  (`id` int NOT NULL COMMENT 'id',`name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,`age` int NULL DEFAULT NULL,`sex` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,`class_name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '课程名',`teacher` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '老师',`score` decimal(10, 2) NULL DEFAULT NULL COMMENT '分数',PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;SET FOREIGN_KEY_CHECKS = 1;-- 库1数据
INSERT INTO `t_stu` VALUES (1, 'andy', 10, '男', '语文', '虚竹', 100.00);

YML

spring:datasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://127.0.0.1:3306/sky_take_out?characterEncoding=utf-8&allowMultiQueries=true&zeroDateTimeBehavior=convertToNull&useSSL=falseusername: rootpassword: root

实体类

package com.suyan.code.test.pojo;import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import com.baomidou.mybatisplus.extension.activerecord.Model;import java.io.Serializable;
import java.math.BigDecimal;
@TableName("t_stu")
public class Stu extends Model<Stu> {@TableId(value = "id",type = IdType.AUTO)private Integer id;private String name;private Integer age;private String className;private BigDecimal score;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public String getClassName() {return className;}public void setClassName(String className) {this.className = className;}public BigDecimal getScore() {return score;}public void setScore(BigDecimal score) {this.score = score;}// getter...// setter...
}

控制层（结论）

        /** 核心：id自增情况下，库里id会回显到 要插入的那个实体上* 结论：在id字段存在，type = IdType.AUTO时，* 插入数据之后。数据的id是可以自动回显到 插入的实体id上的*** 备注：如删除type = IdType.AUTO* 则会导致自增的数据异常（仍然会把异常的id回显）* **///        stuMapper.insert(stu);   //可以生效  id=1
//        System.out.println("stu.getId() = " + stu.getId());//        stuService.save(stu);    //生效  id=2
//        System.out.println("stu.getId()2 = " + stu.getId());//        stuServiceImpl.save(stu);  //生效  id=3
//        System.out.println("stu.getId()3 = " + stu.getId());//        stu.insert(); //生效  id=3
//        System.out.println("stu.getId()4= " + stu.getId());//干掉字段上的自增（会导致自增的字段数据异常）！！！！！！！！！！！！stuMapper.insert(stu);   //能回显，但是id异常   stu.getId() = -738127871System.out.println("stu.getId() = " + stu.getId());

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