如需與 Amazon Timestream for LiveAnalytics 類似的功能，請考慮使用 Amazon Timestream for InfluxDB。它提供簡化的資料擷取和單一位數毫秒查詢回應時間，以進行即時分析。[在這裡](https://docs.aws.amazon.com//timestream/latest/developerguide/timestream-for-influxdb.html)進一步了解。

本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# SELECT
<a name="supported-sql-constructs.SELECT"></a>

**SELECT** 陳述式可用來從一或多個資料表擷取資料。Timestream 的查詢語言支援 SELECT ****陳述式的下列語法：

```
[ WITH with_query [, ...] ]
            SELECT [ ALL | DISTINCT ] select_expr [, ...]
            [ function (expression) OVER (
            [ PARTITION BY partition_expr_list ]
            [ ORDER BY order_list ]
            [ frame_clause ] )
            [ FROM from_item [, ...] ]
            [ WHERE condition ]
            [ GROUP BY [ ALL | DISTINCT ] grouping_element [, ...] ]
            [ HAVING condition]
            [ { UNION | INTERSECT | EXCEPT } [ ALL | DISTINCT ] select ]
            [ ORDER BY order_list ]
            [ LIMIT [ count | ALL ] ]
```

where 
+ `function (expression)` 是支援的[視窗函數](window-functions.md)之一。
+ `partition_expr_list` 是：

  ```
  expression | column_name [, expr_list ]
  ```
+ `order_list` 是：

  ```
  expression | column_name [ ASC | DESC ] 
  [ NULLS FIRST | NULLS LAST ]
  [, order_list ]
  ```
+ `frame_clause` 是：

  ```
  ROWS | RANGE
  { UNBOUNDED PRECEDING | expression PRECEDING | CURRENT ROW } |
  {BETWEEN
  { UNBOUNDED PRECEDING | expression { PRECEDING | FOLLOWING } |
  CURRENT ROW}
  AND
  { UNBOUNDED FOLLOWING | expression { PRECEDING | FOLLOWING } |
  CURRENT ROW }}
  ```
+ `from_item` 是下列其中一項：

  ```
  table_name [ [ AS ] alias [ ( column_alias [, ...] ) ] ]
  from_item join_type from_item [ ON join_condition | USING ( join_column [, ...] ) ]
  ```
+ `join_type` 是下列其中一項：

  ```
  [ INNER ] JOIN
  LEFT [ OUTER ] JOIN
  RIGHT [ OUTER ] JOIN
  FULL [ OUTER ] JOIN
  ```
+ `grouping_element` 是下列其中一項：

  ```
  ()
  expression
  ```