cross apply

cross_apply.sql

SELECT 
    t.Category,
    MIN(j.eventRecordedTime) AS MinEventTime,
    MAX(j.eventRecordedTime) AS MaxEventTime,
    AVG(j.someNumericValue) AS AvgValue
FROM 
    t
    CROSS APPLY OPENJSON(CAST(CAST(t.message AS varchar(max)) AS nvarchar(max)))
    WITH (
        eventRecordedTime datetime2 '$.eventRecordedTime',
        someNumericValue float '$.someNumericValue'
    ) AS j
GROUP BY
    t.Category