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add count window

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54liuyao 2024-07-18 17:12:29 +08:00
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docs/en/12-taos-sql/12-distinguished.md
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@ -38,7 +38,7 @@ select _wstart, tbname, avg(voltage) from meters partition by tbname interval(10
## Windowed Queries
Aggregation by time window is supported in TDengine. For example, in the case where temperature sensors report the temperature every seconds, the average temperature for every 10 minutes can be retrieved by performing a query with a time window. Window related clauses are used to divide the data set to be queried into subsets and then aggregation is performed across the subsets. There are four kinds of windows: time window, status window, session window, and event window. There are two kinds of time windows: sliding window and flip time/tumbling window. The syntax of window clause is as follows:
Aggregation by time window is supported in TDengine. For example, in the case where temperature sensors report the temperature every seconds, the average temperature for every 10 minutes can be retrieved by performing a query with a time window. Window related clauses are used to divide the data set to be queried into subsets and then aggregation is performed across the subsets. There are five kinds of windows: time window, status window, session window, event window, and count window. There are two kinds of time windows: sliding window and flip time/tumbling window. The syntax of window clause is as follows:
```sql
window_clause: {

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docs/zh/12-taos-sql/12-distinguished.md
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@ -39,7 +39,7 @@ select _wstart, tbname, avg(voltage) from meters partition by tbname interval(10
## 窗口切分查询
TDengine 支持按时间窗口切分方式进行聚合结果查询，比如温度传感器每秒采集一次数据，但需查询每隔 10 分钟的温度平均值。这种场景下可以使用窗口子句来获得需要的查询结果。窗口子句用于针对查询的数据集合按照窗口切分成为查询子集并进行聚合，窗口包含时间窗口（time window）、状态窗口（status window）、会话窗口（session window）、事件窗口（event window）四种窗口。其中时间窗口又可划分为滑动时间窗口和翻转时间窗口。
TDengine 支持按时间窗口切分方式进行聚合结果查询，比如温度传感器每秒采集一次数据，但需查询每隔 10 分钟的温度平均值。这种场景下可以使用窗口子句来获得需要的查询结果。窗口子句用于针对查询的数据集合按照窗口切分成为查询子集并进行聚合，窗口包含时间窗口（time window）、状态窗口（status window）、会话窗口（session window）、事件窗口（event window）、计数窗口（count window）五种窗口。其中时间窗口又可划分为滑动时间窗口和翻转时间窗口。
窗口子句语法如下：