mybatis-plus 使用

目录

• mybatis-plus 使用
  • #引入依赖
  • #控制台打印sql
  • #使用
    • 查询 select
    • 插入 insert
    • 更新 upadate
    • 删除 delete

官网: https://mp.baomidou.com/guide/

#引入依赖

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.22</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.3.1</version>
        </dependency>

#控制台打印sql

方法一

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl #开启log日志

方法二

logging:
  level:
    com.chz.mapper: debug

#使用

查询 select

• 通过查询, 查询所有

    @Test 
    public void tests1() {
        List<Employee> employees = employeeDao.selectList(null);
        employees.forEach(System.out::println);

    }

• 按id查询

    @Test 
    public void tests2() {
        Employee employee = employeeDao.selectById(13);
        System.out.println(employee);
    }

• 查询一个

    @Test 
    public void tests3() {
        QueryWrapper<Employee> queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("name","zs")
        Employee employee = employeeDao.selectOne(queryWrapper);
        System.out.println(employee);
    }

• 使用map作为条件查询

    @Test 
    public void tests4() {
        HashMap<String, Object> map = new HashMap<>();
        //key对应字段名, value对应字段值
        map.put("last_name", "z3f");
        List<Employee> employees = employeeDao.selectByMap(map);
        System.out.println(employees);
    }

• 一条记录对应一个map

    @Test 
    public void tests5() {
        QueryWrapper<Employee> queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("gender", 1);
        List<Map<String, Object>> maps = employeeDao.selectMaps(queryWrapper);
        maps.forEach(System.out::println);
    }

• 查询多个id

    @Test
    public void test5() {
        List<Integer> list = Arrays.asList(1, 2, 3);
        List<Employee> employees = employeeDao.selectBatchIds(list);
        employees.forEach(System.out::println);
    }

• 分页查询

  必须配置分页插件

	@Test 
    public void test6() {
        Page<Employee> page = new Page<>(0, 2);
        //queryWrapper可以是null
        IPage<Employee> employeeIPage = employeeDao.selectPage(page, null);
        //要通过getRecords()拿到结果
        System.out.println(employeeIPage.getRecords());
    }

​ 分页插件

    @Bean
    public PaginationInterceptor paginationInterceptor() {
        PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
        return paginationInterceptor;
    }

• 条加查询

    @Test
    public void test7() {
        QueryWrapper<Employee> wrapper = new QueryWrapper<Employee>().select("age", "gender").eq("last_name", "z3f");
        System.out.println(employeeDao.selectOne(wrapper));
    }

• 排序

 	@Test
    public void test8() {
        List<Employee> age = employeeDao.selectList(new QueryWrapper<Employee>().
                orderBy(true, true, "age"));
        System.out.println(age);
    }

• 查询列数

    @Test
    public void test9() {
        //查询带条件的count
        Integer integer = employeeDao.selectCount(new QueryWrapper<Employee>().eq("gender", 1));
        //查询所有的count
        Integer integer1 = employeeDao.selectCount(null);
    }

插入 insert

    @Test
    public void test10() {
        Employee employee = new Employee();
        employee.setLastName("Oka").setEmail("oka@").setGender(2).setAge(3).setSalary(1000D);
        employee.setLastName("z3").setGender(1);
        //insert显示sql当前赋过值的字段
        int num = employeeDao.insert(employee);
        //mp直接会回显主键
        //mybatis需要配置useGeneratedKeys,keyProperty才能回显主键
        Integer id = employee.getId();
        System.out.println("生效行数:" + num + "\t主键值:" + id);
    }

更新 upadate

    @Test
    public void test11() {
        Employee employee = new Employee();
        //如果不想修改某个字段,不赋值即可
        employee.setId(13).setLastName("z3f").setAge(33);
        int i = employeeDao.updateById(employee);
        System.out.println("生效行数:" + i);
    }

支持lambda表达式

@Test
public void tests11() {
    UpdateWrapper<Employee> updateWrapper = new UpdateWrapper<>();
    //where条件
    updateWrapper.lambda()
            .eq(Employee::getLastName, "Black")
            .eq(Employee::getGender, 1);
    Employee employee = new Employee();
    //想要修改的值
    employee.setEmail("black123@qq");
    employeeDao.update(employee, updateWrapper);
}

删除 delete

    @Test 
    public void test12() {
        int i = employeeDao.deleteById(6);
        System.out.println("生效行数:" + i);
    }

    @Test //deleteByMap
    public void test13() {
        HashMap<String, Object> map = new HashMap<>();
        //封装条件
        map.put("age", 22);
        employeeDao.deleteByMap(map);
    }

标签：employee,void,Test,employeeDao,plus,使用,mybatis,new,public
来源： https://www.cnblogs.com/kikochz/p/12912868.html