JSON payload records are imported as VARCHAR. Creating a view allows you to:
- CAST the payload fields to a valid data type
- Rename the header fields using case insensitive naming. Although the example shows the headers in mixed case, you may use any mix of case you want in queries.
The examples use a sample river flow data set. To use your own data, replace the table and column names, and authorization object. See Variable Substitutions for Examples for the credentials and location values for the sample data set.
- To run NOS-related commands, log on to the database as a user with the required privileges.
- If it does not exist, create the foreign table or ask your database administrator to create the foreign table called riverflow_json_path: See Filtering on the Payload Column of a Foreign Table.
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Create a view on the foreign table:
CREATE VIEW riverflowview_json AS ( SELECT CAST(payload.Flow AS FLOAT) ( FORMAT '-ZZZ9.99') Flow, CAST(payload.GageHeight AS FLOAT) ( FORMAT '-ZZZ9.99') GageHeight1, CAST(payload.Precipitation AS FLOAT) ( FORMAT '-ZZZ9.99') Precipitation, CAST(payload.Temp AS FLOAT) ( FORMAT '-ZZZ9.99') Temperature, CAST(payload.Velocity AS FLOAT) ( FORMAT '-ZZZ9.99') Velocity, CAST(payload.BatteryVoltage AS FLOAT) ( FORMAT '-ZZZ9.99') BatteryVoltage, CAST(payload.GageHeight2 AS FLOAT) ( FORMAT '-ZZZ9.99') GageHeight2 FROM riverflow_json_path );
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Query the view:
SELECT TOP 2 * FROM riverflowview_json;
Result:
Flow GageHeight1 Precipitation Temperature Velocity BatteryVoltage GageHeight2 ------ ----------- ------------- ----------- -------- -------------- ----------- 186.00 2.05 0.00 ? ? ? 2.05 232.0 2.16 0.00 ? ? ? 2.16