SQL Server : query columns to JSON object with group by

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 t1GROUP BY ID, ValueV

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

Try this:

SELECT (SELECT [ID], [Keys], [ValueV]  FOR JSON PATH)FROM #Test GROUP BY ID, keys, ValueV

or this:

SELECT (SELECT [ID], [Keys], [ValueV]  FOR JSON PATH, WITHOUT_ARRAY_WRAPPER)FROM #Test GROUP BY ID, keys, ValueV

My two cents:

Interesting that you want valid individual JSON rows and not one single JSON string. Anyhow, here are some alternate answers, although the accepted answer is the best one.

-- 100% hardcoded yourself. Pre SQL Server 2016 SELECT '[{"ID":' + convert(nvarchar(4),T1.[ID]) + ',"ValueV":' + convert(nvarchar(4),T1.[ValueV]) + ',"Keys":["' + T1.[Keys] + '","' + T2.[Keys] + '"]}]' AS [keys]FROM #Test AS T1 INNER JOIN #Test T2 ON t2.ID = t1.ID AND t2.ValueV = t1.ValueV AND t2.keys > t1.keys 

Or:

-- Use the OPENJSON to output your results as a dataset and not just a single row. I've removed the escape character back slashes to match the accepted answers output      SELECT      '[' + REPLACE((REPLACE((REPLACE([value], '\','')),':"[',':[')),']"}',']}') + ']'    FROM OPENJSON(    (SELECT T1.[ID],T1.[ValueV], '["' + T1.[Keys] + '","' + T2.[Keys] + '"]' AS [keys]    FROM #Test AS T1 INNER JOIN #Test T2 ON t2.ID = t1.ID AND t2.ValueV = t1.ValueV AND t2.keys > t1.keys     FOR JSON PATH))

Or:

-- This is a lot cleaner for an array of values in pairs. Again using OPENJSON to output your desired result.  select '[' + [Value] + ']' FROM OPENJSON((select T1.[ID], T1.[ValueV], JSON_MODIFY(JSON_MODIFY('[]','append lax $',t0.keys),'append lax $',t1.keys) as keysFROM #Test AS T0 inner join #Test as t1on  t0.ID = t1.ID AND t0.ValueV = t1.ValueV AND t0.keys < t1.keysFOR JSON path))

Just quick a note that JSON itself is not an object, but just a string of named value pairs, valid JavaScript but a subset nonetheless, it looks completely different when for instance you want a nested Javascript object (If JS is your intended data destination, I'm assuming here). The JSON function's great for quickly pulling off data for transfer, but when you want a nested output or grouping the dataset for an array of values not objects, it can become quite tricky. Personally, since it's a string, for more complicated stuff I just build it myself. Hope that's a different take.