mybatisplus使用常见场景,给我写多一些常用操作题,并给出答案
时间: 2024-04-25 13:06:09 浏览: 16
1. 查询单个实体对象
代码示例:
```java
User user = userMapper.selectById(1);
```
2. 查询所有实体对象
代码示例:
```java
List<User> userList = userMapper.selectList(null);
```
3. 条件查询实体对象
代码示例:
```java
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.eq("name", "张三");
List<User> userList = userMapper.selectList(queryWrapper);
```
4. 分页查询实体对象
代码示例:
```java
Page<User> page = new Page<>(1, 10);
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.eq("age", 18);
IPage<User> userPage = userMapper.selectPage(page, queryWrapper);
List<User> userList = userPage.getRecords();
```
5. 插入实体对象
代码示例:
```java
User user = new User();
user.setName("张三");
user.setAge(18);
userMapper.insert(user);
```
6. 更新实体对象
代码示例:
```java
User user = new User();
user.setId(1);
user.setName("李四");
user.setAge(20);
userMapper.updateById(user);
```
7. 删除实体对象
代码示例:
```java
userMapper.deleteById(1);
```
8. 批量删除实体对象
代码示例:
```java
List<Integer> idList = new ArrayList<>();
idList.add(1);
idList.add(2);
userMapper.deleteBatchIds(idList);
```
9. 条件删除实体对象
代码示例:
```java
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.eq("age", 18);
userMapper.delete(queryWrapper);
```
10. 自定义SQL查询
代码示例:
```java
@Select("select * from user where age = #{age}")
List<User> selectByAge(@Param("age") int age);
```
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