Appointment Slots not working - sql-server

Question

I have three tables.
Table 1.(Booking)
CREATE TABLE [dbo].[Booking](
[Booking_Serno] [int] IDENTITY(1,1) NOT NULL,
[Dt] [datetime] NULL,
[start] [nvarchar](50) NULL,
[todate] [nvarchar](50) NULL,
[Service_Id] [int] NULL
) ON [PRIMARY]
INSERT [dbo].[Booking] ([Booking_Serno], [Dt], [start], [todate], [Service_Id]) VALUES (1, CAST(0x0000A6DA00000000 AS DateTime), N'9:30 AM', N'10:00 AM', 1)
GO
Table 2.(Service)
CREATE TABLE [dbo].[Service](
[Service_Serno] [int] IDENTITY(1,1) NOT NULL,
[Service_Duration] [int] NULL
) ON [PRIMARY]
GO
SET IDENTITY_INSERT [dbo].[Service] ON
INSERT [dbo].[Service] ([Service_Serno], [Service_Duration]) VALUES (1, 30)
Table 3 (Rules)
CREATE TABLE [dbo].[Rules](
[Rule_Serno] [int] IDENTITY(1,1) NOT NULL,
[Start_Dt] [varchar](50) NULL,
[End_Dt] [varchar](50) NULL,
[from_dt] [varchar](50) NULL,
[to_dt] [varchar](50) NULL,
[Service_Id] [int] NULL
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
SET IDENTITY_INSERT [dbo].[Rules] ON
INSERT [dbo].[Rules] ([Rule_Serno], [Start_Dt], [End_Dt], [from_dt], [to_dt], [Service_Id]) VALUES (1, N'2016-07-02', N'2016-07-13', N'07:00', N'17:00', 1)
I am running a stored procedure. It gets me the desired result but then I am trying to book a time by changing the interval, the slots shows empty even if there is a slot booked. Ex. If i am setting a slot for 60 minutes and book a slot from 7:00-8:00 it shows booked(xxx) but when i change the interval to 30 the 7:00-8:00 becomes available. It should actually display 7:00-7:30 and 7:00-8:00 unavailable.
the Stored Procedure is
Dt:-12/12/2016 ; ServiceId:-1
CREATE PROCEDURE [dbo].[RealGetFollowUp] #Dt varchar(50), #ServiceId int
AS
--declare #starttime datetime = '2015-10-28 12:00', #endtime datetime = '2015-10-28 14:00'
DECLARE #starttime varchar(50),
#endtime varchar(50),
#interval int
SELECT
#starttime = Rules.from_dt,
#endtime = Rules.to_dt,
#interval = Service.Service_Duration
FROM Service
INNER JOIN Rules
ON Service.Service_Serno = Rules.Service_Id
WHERE Service.Service_Serno = #ServiceId
--SELECT * INTO #tmp FROM d;
DECLARE #slots int
SELECT
#slots = DATEDIFF(MINUTE, #starttime, #endtime) / #interval
SELECT TOP (#slots)
N = IDENTITY(int, 1, 1) INTO #Numbers
FROM master.dbo.syscolumns a
CROSS JOIN master.dbo.syscolumns b;
SELECT
DATEADD(MINUTE, ((n - 1) * #interval), #starttime) AS start,
DATEADD(MINUTE, (n * #interval), #starttime) AS todate INTO #slots
FROM #numbers
SELECT
#Dt AS 'Date',
LEFT(CONVERT(varchar, s.start, 108), 10) AS Start,
LEFT(CONVERT(varchar, s.todate, 108), 10) AS 'End',
CASE
WHEN b.start IS NULL THEN '-'
ELSE 'xx'
END AS Status
FROM [#slots] AS s
LEFT JOIN Booking AS b
ON s.start = b.start
AND s.todate = b.todate
AND b.Dt = #Dt
DROP TABLE #numbers, #slots
GO
I need to check if there is a slot booked in the Booking table and even if i change the interval in the service table, the slot booked in the booking table should be shown as booked.

Answer 1

Change the output SELECT in the sproc to...
SELECT
#Dt AS 'Date',
LEFT(CONVERT(varchar, s.start, 108), 10) AS Start,
LEFT(CONVERT(varchar, s.todate, 108), 10) AS 'End',
CASE
WHEN b.start IS NULL THEN '-'
ELSE 'xx'
END AS Status
FROM [#slots] AS s
LEFT JOIN Booking AS b
ON (
--Range is bigger than the meeting
(s.start <= b.start
AND s.todate >= b.todate)
OR
--Range is smaller than the meeting
(s.start Between b.start and b.toDate
AND s.todate Between b.start and b.toDate)
)
AND b.Dt = #Dt