IF object_id('fn_MountainsPeaksJSON') IS NOT NULL
BEGIN
    PRINT 'Dropping function'
    DROP FUNCTION fn_MountainsPeaksJSON
    IF @@ERROR = 0 PRINT 'Function dropped'
END
GO

CREATE FUNCTION fn_MountainsPeaksJSON  ()
RETURNS  VARCHAR(MAX)
BEGIN
   DECLARE mountains CURSOR FOR
    SELECT dbo.Mountains.MountainRange, dbo.Mountains.Id
    FROM Mountains


    OPEN mountains;
    DECLARE @mountainRange VARCHAR(50), @mountainId INT, @JSONString VARCHAR(MAX);
    SET @JSONString = '{"mountains":[';

    FETCH NEXT FROM mountains INTO @mountainRange, @mountainId
    WHILE @@FETCH_STATUS = 0
    BEGIN
       DECLARE @PartJSONString VARCHAR(MAX) = '{"name":"' + @mountainRange + '"';

       DECLARE peaks CURSOR FOR
       SELECT dbo.Peaks.PeakName, dbo.Peaks.Elevation
       FROM Peaks
       WHERE dbo.Peaks.MountainId = @mountainId
       ORDER BY dbo.Peaks.Id ASC

       OPEN peaks;
       DECLARE @peaksJSONString VARCHAR(MAX) = NULL, @peakName VARCHAR(50), @peakElevation INT;

       FETCH NEXT FROM peaks INTO @peakName, @peakElevation;

       WHILE @@FETCH_STATUS = 0
       BEGIN
          IF @peaksJSONString IS NULL
          BEGIN
             SET @peaksJSONString = ',"peaks":[' + '{"name":"' + @peakName + '","elevation":' + CAST(@peakElevation AS VARCHAR) + '}'
          END
          ELSE
          BEGIN
          SET @peaksJSONString = @peaksJSONString + ',{"name":"' + @peakName + '","elevation":' + CAST(@peakElevation AS VARCHAR) + '}';
          END
          FETCH NEXT FROM peaks INTO @peakName, @peakElevation;
       END;

       CLOSE peaks;
       DEALLOCATE peaks;

       IF @peaksJSONString IS NOT NULL
       BEGIN
          SET @peaksJSONString = @peaksJSONString + ']';
          SET @PartJSONString = @PartJSONString  + @peaksJSONString;
       END
       ELSE
       BEGIN
          SET @PartJSONString = @PartJSONString + ',"peaks":[]'
       END

       SET @PartJSONString = @PartJSONString + '}'

       SET @JSONString = @JSONString + @PartJSONString + ',';
       FETCH NEXT FROM mountains INTO @mountainRange, @mountainId
    END;

    CLOSE mountains;
    DEALLOCATE mountains;

    RETURN LEFT(@JSONString, LEN(@JSONString) -1) + ']}'
END;

SELECT  dbo.fn_MountainsPeaksJSON ()