@Getter
@Setter
public class User {
private Long id;
private String userName;
private String userAge;}
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②、创建UserMapper 接口
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.ys.mybatisplusstudy.entry.User;
public interface UserMapper extends BaseMapper<User>{}
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③、启动类增加@MapperScan注解
@SpringBootApplication
@MapperScan("com.ys.mybatisplusstudy.mapper")
public class MybatisplusstudyApplication {
public static void main(String[] args){
SpringApplication.run(MybatisplusstudyApplication.class, args);}}
public interface UserMapper extends BaseMapper<User>{}
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我们进入到 BaseMapper 内部,发现其结构如下:
这些方法便是我们常用的增删改查了,下面我们分别演示几个常用的。
①、insert:新增一条记录
@SpringBootTest
class MybatisplusstudyApplicationTests {
@Autowired
private UserMapper userMapper;/** * 新增一条记录 */
@Test
public void testInsert(){
User user = new User();
user.setId(3L);
user.setUserName("test insert");
user.setUserAge("1");intinsert= userMapper.insert(user);
System.out.println("影响记录数:"+insert);}}
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执行完毕后,我们查看数据库:
②、delete:删除记录
/** * 根据id删除一条记录 */
@Test
public void testDeleteById(){int num = userMapper.deleteById(3L);
System.out.println("删除的记录数为:"+num);
QueryWrapper wrapper = new QueryWrapper();
wrapper.eq("id",3L);
userMapper.delete(wrapper);}/** * 构造相关条件删除记录 */
@Test
public void testDelete(){
QueryWrapper wrapper = new QueryWrapper();
wrapper.eq("USER_NAME","test insert");int num = userMapper.delete(wrapper);
System.out.println("删除的记录数为:"+num);}
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③、update:修改记录
/** * 根据id修改 */
@Test
public void testudpateById(){
User user = new User();
user.setId(3L);
user.setUserName("test update");int num = userMapper.updateById(user);
System.out.println("修改的记录数为:"+num);}