you can solve it by stored procedure.
CREATE PROCEDURE CHECKMEETINGDATE
(
@TXTDATE1 NVARCHAR(10)
, @TXTDATE2 NVARCHAR(10)
)
AS
BEGIN
SET NOCOUNT ON
IF(SELECT TOP 1 1 FROM Meeting WHERE @TXTDATE1 BETWEEN start_date AND end_date)
BEGIN
SELECT 'Already Booked'
END
ELSE IF (SELECT TOP 1 1 FROM Meeting WHERE @TXTDATE2 BETWEEN start_date AND end_date)
BEGIN
END
SELECT 'Already Booked'
ELSE
BEGIN
SELECT 'Available'
END
SET NOCOUNT OFF
END