Convertir Tabla a Json con SQL Server < 2016

tableToJson.sql

ALTER PROCEDURE dbo.GetJSON @ObjectName VARCHAR(255), @registries_per_request smallint = null
AS
BEGIN
	IF OBJECT_ID(@ObjectName) IS NULL
		BEGIN
			SELECT Json = '';
			RETURN
		END
	--SELECT CAST('<xml>Yep this is xml</xml>' AS XML)
	DECLARE @Top NVARCHAR(20) = CASE WHEN @registries_per_request IS NOT NULL THEN 'TOP (' + CAST(@registries_per_request AS NVARCHAR) + ') ' ELSE '' END;
	DECLARE @SQL NVARCHAR(MAX) = N'SELECT ' + @Top + '* INTO ##T FROM ' + @ObjectName;

	EXECUTE SP_EXECUTESQL @SQL;

	DECLARE @X xml = CAST( (SELECT * FROM ##T FOR XML PATH, root) AS XML);

	SELECT '[' +
		STUFF(  
			(SELECT * FROM  
				(
				SELECT 
				',{' + 
					STUFF( 
						(
						SELECT ',"' + COALESCE(b.c.value('local-name(.)','NVARCHAR(MAX)'),'') + '":'
								+ ( IIF( ISNUMERIC(b.c.value('text()[1]','NVARCHAR(MAX)'))=1, b.c.value('text()[1]','NVARCHAR(MAX)'), '"'+b.c.value('text()[1]','NVARCHAR(MAX)')+'"') ) 
						FROM x.a.nodes('*') b(c) FOR XML PATH(''),TYPE
						).value('(./text())[1]','NVARCHAR(MAX)') ,1, 1, ''
					) + 
				'}' 
				FROM @X.nodes('/root/*') x(a)  
				)
				JSON(theLine) FOR XML PATH(''),TYPE
			).value('.','NVARCHAR(MAX)' )
			, 1, 1, ''
		)
	+']'
	DROP TABLE ##T;
	--SELECT	Json = @X;
END

-- Tabla Clave Valor
CREATE TABLE T
(	ID INT IDENTITY(1, 1) NOT NULL,
	Col1 INT NOT NULL
);
INSERT dbo.T (Col1)
-- Llenando tabla 'T'
SELECT	TOP 10 Number FROM Master..spt_values WHERE Type = 'P';

-- Tabla con varios tipos de valor (string y numeric)
CREATE TABLE TS
(	cod INT IDENTITY(1, 1) NOT NULL,
	val NVARCHAR(500) DEFAULT '',
	ext INT DEFAULT 0
);
-- Llenando tabla TS
INSERT INTO TS VALUES ('val2',1),('val3',0),('val4',1),('val5',0);

-- Tabla con muchas columnas
CREATE TABLE T2
(	ID INT IDENTITY(1, 1) NOT NULL,
	Col1	INT NOT NULL,
	Col2	INT NOT NULL,
	Col3	INT NOT NULL,
	Col4	INT NULL
);
-- Llenando tabla TS
INSERT dbo.T2 (Col1, Col2, Col3)
SELECT TOP 10 Number, Number, Number FROM Master..spt_values WHERE Type='P';
GO
-- example execute
EXECUTE dbo.GetJSON 'dbo.TS', 2;