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Table and Store Example

This example shows how tables and database-backed stores can be used to store events.

Example​

-- Defines `TemperatureStream` stream having `sensorId` and `temperature` attributes of types `string` and `double`.
CREATE STREAM TemperatureStream (sensorId string, temperature double);

-- Defines `TemperatureLogTable` having `sensorId`, `roomNo`, and `temperature` attributes of types `string`, `string`, and `double`.
CREATE TABLE GLOBAL TemperatureLogTable (sensorId string, roomNo string, temperature double);

-- Defines `SensorIdInfoTable` table.
CREATE TABLE GLOBAL SensorIdInfoTable (sensorId string, roomNo string);

@info(name = 'Join-query')
-- Selects `sensorId`, `roomNo`, and `temperature` attributes from stream and table, and adds events to `TemperatureLogTable`.
INSERT INTO TemperatureLogTable
SELECT t.sensorId AS sensorId, s.roomNo AS roomNo, t.temperature AS temperature
FROM TemperatureStream AS t JOIN SensorIdInfoTable AS s
     ON t.sensorId == s.sensorId;

Event at Table and Store​

When SensorIdInfoTable table contains a recode ['aq-14', '789'], and when an event with values ['aq-14', 35.4] is sent to TemperatureStream stream.

The event will get converted and added to the TemperatureLogTable table as below.

['aq-14', '789', 35.4]

Retrieve Values from Tables and Stores​

The stored values can be retrieved by joining tables and stores with the streams as in the Join-query depicted in the example, or using on-demand queries.

The data in TemperatureDetailsTable can be retrieved using on-demand queries as shown below, using the On Demand Query REST API.

SELECT *
FROM TemperatureDetailsTable