SQL Server : query columns to JSON object with group by

Question

I have a table with 3 columns, I want to query that table such that the result will be a JSON object.

Sample data looks like this:

 CREATE TABLE #Test (         


        

Answer 1

This works (in SQL Server 2017, where STRING_AGG is available), but is quite clumsy. I'm not sure there's not a more elegant way.

SELECT (
    SELECT 
       ID, 
       ValueV, 
       Keys = JSON_QUERY('["' + STRING_AGG(STRING_ESCAPE(Keys, 'json'), '","') + '"]')
    FOR JSON PATH
)
FROM #Test 
GROUP BY ID, ValueV

For SQL Server 2016 (which has no STRING_AGG, or STRING_ESCAPE for that matter):

SELECT (
    SELECT ID, ValueV, Keys = JSON_QUERY(REPLACE(REPLACE(
        (
            SELECT Keys 
            FROM #Test t2 WHERE t2.ID = t1.ID AND t2.ValueV = t1.ValueV 
            FOR JSON PATH
        ),
        '{"Keys":', ''),
        '}', ''))
    FOR JSON PATH
)
FROM #Test t1
GROUP BY ID, ValueV

Even less elegant, but you take what you can get. At least we're not concatenating with FOR XML...