1 . SimpleDAO From Zero To Production: Single-table CRUD, Audit Fields & Soft Delete

pom.xml
src/main/java/example/
  DemoApplication.java
  user/
    User.java        -- entity
    UserDao.java     -- data access
    UserCond.java    -- query conditions
src/main/resources/
  application.yml
  schema.sql

@Data @Builder
@Table("sys_user")
public class User {
    @Id private Long id;
    private String name;
    private Integer age;
    private String email;
    // ... other fields

    // These four are auto-managed:
    private LocalDateTime createTime;
    private Long createBy;
    private LocalDateTime updateTime;
    private Long updateBy;
    private Byte dr;  // 0 = active, 1 = soft-deleted
}

@Repository
public class UserDao extends BaseDao<User> {
    // Empty. All CRUD methods inherited.
}

@Getter @Setter @Builder
public class UserCond extends BaseCondition {
    private String name;
    private Integer ageMin;
    private Integer ageMax;
    private Byte dr;
    private Object[] ids;

    @Override
    protected void addCondition() {
        and("name LIKE", name, 3);   // 3 = %value%
        and("age >=", ageMin);
        and("age <=", ageMax);
        and("dr =", dr);
        in("id", ids);
    }
}

@Autowired UserDao userDao;

public void demo() {
    // Insert
    User user = User.builder().name("John").age(25).email("john@example.com").build();
    userDao.save(user);  // id, createTime, createBy, dr auto-filled

    // Query by ID
    User found = userDao.findById(user.getId());

    // Paginated search
    Page<User> page = userDao.page(
        UserCond.builder().name("John").ageMin(20).ageMax(30).build()
    );

    // Update
    found.setAge(26);
    userDao.update(found);  // updateTime, updateBy auto-filled

    // Soft delete (dr=1, not DELETE)
    userDao.delete(found.getId());
}

-- save()
INSERT INTO sys_user (id,name,age,email,create_time,create_by,dr) 
VALUES (3679201737291333632,'John',25,'john@example.com','2026-04-10 13:14:10',1000,0)

-- page()
SELECT COUNT(1) FROM sys_user t 
WHERE t.name LIKE '%John%' AND t.age >= 20 AND t.age <= 30

SELECT t.id,t.name,t.age,t.email FROM sys_user t 
WHERE t.name LIKE '%John%' AND t.age >= 20 AND t.age <= 30 
LIMIT 0,10

-- delete() with dr field present
UPDATE sys_user t SET dr=1 WHERE id IN (3679201737291333632)