# 使用 `.` 表示法筛选数组
<a name="filtering-with-dot"></a>

在以下示例中，使用点 `.` 表示法从 Amazon CloudTrail 日志表的 `userIdentity` 列中选择 `accountId` 字段。有关更多信息，请参阅[查询 Amazon CloudTrail 日志](cloudtrail-logs.md)。

```
SELECT
  CAST(useridentity.accountid AS bigint) as newid
FROM cloudtrail_logs
LIMIT 2;
```

此查询返回：

```
+--------------+
| newid        |
+--------------+
| 112233445566 |
+--------------+
| 998877665544 |
+--------------+
```

要查询一个值数组，请发出以下查询：

```
WITH dataset AS (
  SELECT ARRAY[
    CAST(ROW('Bob', 38) AS ROW(name VARCHAR, age INTEGER)),
    CAST(ROW('Alice', 35) AS ROW(name VARCHAR, age INTEGER)),
    CAST(ROW('Jane', 27) AS ROW(name VARCHAR, age INTEGER))
  ] AS users
)
SELECT * FROM dataset
```

它将返回此结果：

```
+-----------------------------------------------------------------+
| users                                                           |
+-----------------------------------------------------------------+
| [{NAME=Bob, AGE=38}, {NAME=Alice, AGE=35}, {NAME=Jane, AGE=27}] |
+-----------------------------------------------------------------+
```