今天开始学MyBatis-Plus,没有用过,所以边学习变记录一下,学习记录是根据视频学习,视频连接https://www.imooc.com/learn/1130;
一、创建表和插入数据
1.先创建表:
create table user(
id BIGINT(32) PRIMARY key not null COMMENT '主键',
name varchar(30) DEFAULT null COMMENT '姓名',
age int(11) DEFAULT NULL COMMENT '年龄',
email VARCHAR(50) DEFAULT NULL COMMENT '邮箱',
manager_id BIGINT(20) DEFAULT NULL COMMENT '直属上级id',
create_time datetime DEFAULT NULL COMMENT '创建时间',
CONSTRAINT manager_fk FOREIGN key(manager_id)
REFERENCES user(id)
)ENGINE=INNODB CHARSET=utf8;
2.插入一些数据:
INSERT into user(id,name,age,email,manager_id,create_time)
VALUES(1111111111,'老板',50,'boss@qq.com',null,'2020-01-04 22:20:00'),
(1111122222,'经理',34,'jl@qq.com',1111111111,'2020-01-04 22:20:00'),
(1111133333,'员工1',23,'yg1@qq.com',1111122222,'2020-01-04 22:20:00'),
(1111144444,'员工2',25,'yg2@qq.com',1111122222,'2020-01-04 22:20:00'),
(1111155555,'员工3',21,'yg3@qq.com',1111122222,'2020-01-04 22:20:00'),
(1111166666,'员工4',27,'yg4@qq.com',1111122222,'2020-01-04 22:20:00');
二、创建Springboot项目:
1.创建好后添加依赖:
<!--mybatis jdbc驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.2.0</version>
</dependency>
<!--mybatis-plus 启动器-->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.1.0</version>
</dependency>
2.在项目下创建包:
3.创建实体类User:
private Integer id;
private String name;
private int age;
private String email;
private Integer managerId;
private Date createTime;
4.创建接口UserMapper继承BaseMpper
5.通过selectList()方法查询所有:
总结遇到的坑:
1.不要添加mybatis依赖,因为添加了mybatis-plus依赖
2.连接数据库驱动要用:com.mysql.cj.jdbc.Driver
3.在启动类上要加上UserMapper所在路径@MapperScan(“com.*.dao”)
3.连接数据库时后面要加useSSL=false&serverTimezone=GMT%2B8,不然会报时间错误;