mybatis-plus入门

1.创建数据库

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for blog
-- ----------------------------
DROP TABLE IF EXISTS `blog`;
CREATE TABLE `blog`  (
  `id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,
  `name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL,
  PRIMARY KEY (`id`) USING BTREE,
  INDEX `name`(`name`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 11 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of blog
-- ----------------------------
INSERT INTO `blog` VALUES (7, '1');
INSERT INTO `blog` VALUES (8, '2');
INSERT INTO `blog` VALUES (9, '3');

-- ----------------------------
-- Table structure for blog_tag
-- ----------------------------
DROP TABLE IF EXISTS `blog_tag`;
CREATE TABLE `blog_tag`  (
  `id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT,
  `bid` int(11) UNSIGNED NOT NULL,
  `tid` int(11) UNSIGNED NOT NULL,
  PRIMARY KEY (`id`) USING BTREE,
  INDEX `1`(`bid`) USING BTREE,
  INDEX `tid`(`tid`) USING BTREE,
  CONSTRAINT `1` FOREIGN KEY (`bid`) REFERENCES `blog` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `blog_tag_ibfk_1` FOREIGN KEY (`tid`) REFERENCES `tag` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE = InnoDB AUTO_INCREMENT = 5 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of blog_tag
-- ----------------------------
INSERT INTO `blog_tag` VALUES (4, 7, 6);

-- ----------------------------
-- Table structure for tag
-- ----------------------------
DROP TABLE IF EXISTS `tag`;
CREATE TABLE `tag`  (
  `id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,
  `content` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 7 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of tag
-- ----------------------------
INSERT INTO `tag` VALUES (4, 'B');
INSERT INTO `tag` VALUES (6, 'A');

SET FOREIGN_KEY_CHECKS = 1;

2.导入依赖

		
            mysql
            mysql-connector-java
        
		
            org.projectlombok
            lombok
            true
        

        
            com.baomidou
            mybatis-plus-boot-starter
            3.4.3.4
        

3.配置application.yml

spring:
  devtools:
    restart:
      enabled: true
      additional-paths: src/main/java
  datasource:
    username: root
    password: ******
    url: jdbc:mysql://localhost:3306/study
    driver-class-name: com.mysql.cj.jdbc.Driver
server:
  port: 8084

4.实体类、mapper层

blog实体类

package com.sj.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.sun.corba.se.spi.orbutil.fsm.Input;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;


@Data
@AllArgsConstructor
@NoArgsConstructor
public class Blog {
    @TableId(type = IdType.AUTO)
    private  int id;
    private String name;
}

mapper

package com.sj.mapper;

import com.baomidou.mybatisplus.core.mapper.baseMapper;
import com.sj.entity.Blog;
import org.springframework.stereotype.Repository;

import java.util.List;


@Repository
public interface BlogMapper extends baseMapper {
    List selectList();
}

package com.sj;

import com.sj.entity.Blog;
import com.sj.mapper.BlogMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import javax.sound.midi.Soundbank;
import java.util.List;

@SpringBootTest
class MybatiPlusApplicationTests {

    @Autowired
    BlogMapper blogMapper;

    @Test
    void contextLoads() {
        List blogs = blogMapper.selectList();
        System.out.println(blogs);
    }
    @Test
    void insert(){
        Blog blog=new Blog();
        blog.setName("demo");
        int insert = blogMapper.insert(blog);
        System.out.println(insert);
        System.out.println(blog);
    }
    @Test
    void update(){
        Blog blog=new Blog();
        blog.setName("update");
        blog.setId(15);
        int i = blogMapper.updateById(blog);
        System.out.println(i);
        System.out.println(blog);
    }
    @Test
    void delete(){
        Blog blog=new Blog();
        blog.setId(14);
        int i = blogMapper.deleteById(blog);
        System.out.println(i);
        System.out.println(blog);
    }

}

查询结果：

添加：

更新：

删除：