Check Hall Booking status - sql

Question

I'm making a Hall Booking System, and I've being struggling with the Booking Module
I have 2 tables Halls & Bookings
Halls table With Sample Data
id hallName hallType numSeats status
---------------------------------------------
1 Hall 1 Normal 500 active
2 Hall 2 VIP 30 active
3 Hall 3 VVIP 5 active
4 Hall 4 Normal 60 active
5 Hall 5 Normal 80 active
6 Hall 4+5 Normal 140 active
Booking Table with Sample Data
id custId hallId beginDate endDate time status
-----------------------------------------------------------------
1 1 1 2022-09-26 2022-09-26 morning confirmed
2 6 4 2022-09-26 2022-09-26 evening cancelled
3 4 3 2022-09-26 2022-09-26 full time pending
4 9 4 2022-09-26 2022-09-30 after noon confirmed
Booking time slots are "morning", "after noon", "evening" & "full time"
I have being trying on the Booking validations as well as a report that shows Halls booking status
Edit
After suggestions in the comments I have edited and removed the second part, maybe will post seperately if I can't figure out
Here is what I want to be the result
The records can be filtered by endDate(e.g 2022-09-26)
if Booking exists which is not cancelled for the provided beginDate, the time slot should be labelled as Booked
if a booking does not exist for the provided beginDate or its canclled, the time slot should be labeled as Available
If a full time Booking slot ecists for the provied beginDate, all the time the 3 slots should be labeled as Booked
Here is the twist that may complicate things
As you can see from the Halls table, Hall 6 is a combination of Halls 4 & 5 which means if any of them is booked, Hall 6 should be marked as unavailable or even Booked will be fine.
Overall, here is a sample result based on the above booking table
hallName hallType morning after noon evening
------------------------------------------------------
hall 1 Normal Booked available available
hall 2 VIP available available available
hall 3 VVIP Booked Booked Booked
hall 4 Normal available Booked available
hall 5 Normal available available available
hall 6 Normal available unavailable available
if we take the Booking Table with Sample data, the result should be as shown above
I'm not that much familiar with Joins, merges, etc which are what I'm thinking the solution is. I tried merge with When matched and when Not matched but could not figure it out to work
I then tried left joining the Halls table to the Booking table seems to be the closest so far and the output is clear.
DECLARE #date NVarchar(50) = '2022-09-26'
SELECT h.id, h.hallName, h.hallType, b.time FROM Halls h LEFT JOIN
Bookings b ON b.hallId=h.id WHERE b.beginDate=#date
this returns only Booked halls with beginDate of that
If I drop the WHERE clause, all the 6 halls are returned but time slots which aren't booked are returned as NULL
btw I'm working on the last module and at firts I was working with a single check in date and requirement changed into Range beginDate & endDate & that is when problems arose.

Answer 1

Firstly you need to fix your design how are you intend to store information that Hall 6 is a combine of Hall 4 + 5
One simple way is to add another column in the Halls table that indicate that. Example
create table Halls
(
id int,
hallName varchar(10),
hallType varchar(10),
numSeats int,
status varchar(10),
combine_id int
);
insert into Halls values
(4, 'Hall 4', 'Normal', 60, 'active', 6),
(5, 'Hall 5', 'Normal', 80, 'active', 6),
(6, 'Hall 4+5', 'Normal', 140, 'active', null);
Once that is in-placed, you need to translate the Bookings to handle the combined Halls. This is perform by the CTE BookingData. It will create row for Hall 6 if Hall 4 or Hall 5 is pending or confirmed. And simiarly the other way round. When Hall 6 is Booked, Hall 4 and Hall 5 will be unavailable.
After that it is just simple pivoting of data
The solution:
DECLARE #date date = '2022-09-26';
with BookingData as
(
select b.hallId, b.time, b.status, beginDate
from Bookings b
union all
select hallId = h.combine_id, b.time,
status = case when b.status in ('pending', 'confirmed')
then 'unavailable'
else 'available'
end,
beginDate
from Bookings b
inner join Halls h on b.hallId = h.id
where h.combine_id is not null
union all
select hallId = h.id, b.time,
status = case when b.status in ('pending', 'confirmed')
then 'unavailable'
else 'available'
end,
beginDate
from Bookings b
inner join Halls h on b.hallId = h.combine_id
where h.combine_id is not null
)
SELECT id,
hallName,
hallType,
[morning] = isnull([morning], 'available'),
[afternoon] = isnull([afternoon], 'available'),
[evening] = isnull([evening], 'available')
FROM
(
SELECT h.id, h.hallName, h.hallType, t.timeSlot,
status = case when b.status in ('pending', 'confirmed')
then 'Booked'
when b.status in ('cancelled')
then 'unavailable'
when b.status in ('unavailable')
then b.status
else NULL
end
FROM Halls h
LEFT JOIN BookingData b ON b.hallId = h.id
and b.beginDate = #date
OUTER APPLY
(
select timeSlot = 'morning' where b.time in ('morning', 'full time')
union all
select timeSlot = 'afternoon' where b.time in ('afternoon', 'full time')
union all
select timeSlot = 'evening' where b.time in ('evening', 'full time')
) t
) D
PIVOT
(
MAX (status)
FOR timeSlot in ( [morning], [afternoon], [evening] )
) P
db<>fiddle demo

Answer 2

Your question is overtly complicated due to the fact the table does not implement normalization properly for "combined halls." We will need to separate Hall 4+5 using string operation and then store the extracted information somewhere. Here is the query that I could think off:
with
composite_halls as
(select *,
substring(hallName, charindex(' ', hallName) + 1,
charindex('+', hallName) - charindex(' ', hallName) - 1) as id1,
right(hallName, len(hallName) - charindex('+', hallName)) as id2,
(null) as id3
from halls where charindex('+', hallName) > 0),
singular_halls as
(select *,
(select ch.id2 from composite_halls as ch where ch.id1 = h.id) as id1,
(select ch.id1 from composite_halls as ch where ch.id2 = h.id) as id2,
(select ch.id from composite_halls as ch where ch.id1 = h.id or ch.id2 = h.id) as id3
from halls as h where charindex('+', hallName) = 0),
all_halls as (
select * from singular_halls
union
select * from composite_halls),
valid_bookings as (
select * from bookings where status = 'confirmed'
and beginDate >= '2022-09-26' and endDate <= '2022-09-26')
select *,
(case when exists (
select *
from valid_bookings as vb
where (time = 'morning' or time = 'full time')
and (vb.hallId = h.id
or (vb.hallId = h.id1 and h.id3 is null)
or (vb.hallId = h.id2 and h.id3 is null)
or vb.hallId = h.id3))
then 'booked'
else 'available'
end) as morning
from all_halls as h
You can try it on fiddle: https://dbfiddle.uk/baQyI1Y7
It looks somewhat detestable and I believe someone else can write shorter queries.
The query above uses 4 CTEs with 3 of them deals with extracting the ids of relevant "combined halls." composite_halls will extract the numbers from hallName and puts them into id1 and id2. singular_halls will put its counterpart's id in either id1 or id2 and its composite in id3. all_halls merges the two result into one. valid_bookings filters bookings for given timeframe and only confirmed bookings are taken.
The next step, it checks if any bookings' hallId correspond to any of id, id1, id2, id3 within the all_halls entries. So far it only handles morning bookings and only provide booked and available status. You can expand it to provide unavailable by adding more case when to specifically handle id1 up to id3. You can handle after noon and evening can be done the same way by changing the time parameter within the case when clause.
I don't think the query above is performant enough for a live application. Especially the fact that we operate on row-by-row basis to extract the relevant halls from the "combined" one.
I believe things would be much easier should you normalize the table a bit more. I feel its like doing excel using TSQL which doesn't seem right.