children.md

# 查找子节点

有一个表 node，有两列

```shell
# select item from node;
id  | pid
------------------
1   | 0
2   | 1
3   | 1
4   | 3
5   | 2
...   
```

其中id是自增主键，pid指向父节点的id。那么给定某一个id ，查找它的子节点的查询应该是：

## 答案

```sql
select * from node where pid = ?
```

## 选项

### 缺少 where

```sql
select * from node pid = ?
```

### 结构错误

```sql
from node select * where pid = ?
```

### select 不完整

```sql
select from node where pid = ?
```