CREATE TABLE Checador(
	tarjeta		int,
	hora		datetime,
	fecha		date,
	reloj		int)
INSERT Checador VALUES
(30 , '02/08/2010 08:14' , '02/08/2010' , 1 ),
(30 , '02/08/2010 12:57' , '02/08/2010' , 1 ),
(30 , '02/08/2010 14:01' , '02/08/2010' , 1 ),
(30 , '02/08/2010 19:21' , '02/08/2010' , 1 ),
(35 , '02/08/2010 07:23' , '02/08/2010' , 1 ),
(35 , '02/08/2010 13:05' , '02/08/2010' , 1 ),
(16 , '02/08/2010 12:58' , '02/08/2010' , 1 );

WITH CTE AS(
	SELECT tarjeta,
		hora,
		fecha,
		reloj,
		ROW_NUMBER() OVER( PARTITION BY tarjeta, fecha ORDER BY hora) % 2 AS inicio,
		(ROW_NUMBER() OVER( PARTITION BY tarjeta, fecha ORDER BY hora) + 1) / 2 AS numero
	FROM Checador)
SELECT tarjeta,
		MAX( CASE WHEN inicio = 1 THEN hora END) hora_inicio,
		MAX( CASE WHEN inicio = 0 THEN hora END) hora_termino,
		fecha,
		reloj
FROM CTE
GROUP BY tarjeta,
	fecha,
	reloj,
	numero

DROP TABLE Checador

declare @Checador TABLE (
	i int identity (1,1),
	TARJETA 		int,
	HORA  datetime,
	FECHA 		date,
	RELOJ 		int)
INSERT @Checador VALUES
(30 , '02/08/2010 08:14' , '02/08/2010' , 1 ),
(30 , '02/08/2010 12:57' , '02/08/2010' , 1 ),
(30 , '02/08/2010 14:01' , '02/08/2010' , 1 ),
(30 , '02/08/2010 19:21' , '02/08/2010' , 1 ),
(35 , '02/08/2010 07:23' , '02/08/2010' , 1 ),
(35 , '02/08/2010 13:05' , '02/08/2010' , 1 ),
(16 , '02/08/2010 12:58' , '02/08/2010' , 1 );

;with cte   as 
(
	select ch.i,ch.TARJETA ,ch.HORA as HORA_INICIO  ,ch1.HORA  as HORA_TERMINO  ,ch.FECHA ,ch.RELOJ 
	from @Checador ch
	left join @Checador ch1
	on ch.i+1=ch1.i 
)

select TARJETA,HORA_INICIO,HORA_TERMINO,FECHA,RELOJ
from cte where i%2<>0