SQL检查日期之间是否有空房间

Question

I have a question in reference to a query to the database. I have this table:

In another window, i have a form with start and end date inputs and I want to do a sql to confirm if the room 23 is available between this dates, every day. I try with this sql:

SELECT * FROM this_table 
WHERE room_type_id=23 
AND date="2018-03-06 00:00:00" 
AND date="2018-03-07 00:00:00" 
AND date="2018-03-08 00:00:00" 
AND date="2018-03-09 00:00:00"

This query doesn't work because is checking if any row has all the dates.

My question is: How can i check if the room is available on this days?

Answer 1

This will answer your particular question with yes or no. I'm not sure it's useful since the date search values are all specific in a hard-coded list.

select coalesce(max('no'), 'yes') as available
from tbl t           
where room_type_id = 23 and
    dt in ("2018-03-06 00:00:00", "2018-03-07 00:00:00", 
           "2018-03-08 00:00:00", "2018-03-09 00:00:00");

If the sense of your logic is intended to find at least one open date then you might try something like this:

select case when count(*) = 4 then 1 else 0 end as whatever_this_means
from tbl t
where room_type_id = 23 and
    dt in ("2018-03-06 00:00:00", "2018-03-07 00:00:00", 
           "2018-03-08 00:00:00", "2018-03-09 00:00:00");

The problem is going to be that you've hard-coded the value 4 now which is tied to the number of dates in the list later in the query. There are ways to handle this more dynamically but it's not entirely clear from your question the best way to do that.

Answer 2

Perhaps using OR instead of AND between the dates?

SELECT * FROM this_table 
WHERE room_type_id=23 AND 
(date="2018-03-06 00:00:00" OR
date="2018-03-07 00:00:00" OR
date="2018-03-08 00:00:00" OR
date="2018-03-09 00:00:00")

Answer 3

shawnt00 gives me a good idea. I modify a little this query changing the yes and no responses and it works for me.

select case when count(*) < 4 then 'no' else 'yes' end as available
from room_type_day t
where room_type_id = 23 and
    date in ("2018-03-07 00:00:00","2018-03-08 00:00:00","2018-03-09 00:00:00","2018-03-10 00:00:00");

Answer 4

if you store room info inside db when somebody reserve it the every record show that the room is not empty at it's date, now if you have another table that store room names you can select rooms that not exists any date for them

SELECT room_id FROM rooms WHEN room_id NOT IN (SELECT room_id FROM reserveTable WHERE date BETWEEN @StartDate AND @EndDate)

but if you store empty rooms in db(it may be a dirty database ;-) ) you can select rooms that are between your dates,

SELECT room_id FROM reserveTable WHEN date BETWEEN @StartDate AND @ EndDate

finally, it depends to your database structure, and your form definition.
i hope this help you to find a good solution

Answer 5

If 'this_table' store available room then you can return 0 or 1 with this trick :

Count the number of days available :

SELECT room_type_id, Count(*) as Av_days
FROM this_table
WHERE room_type_id=23 AND date BETWEEN @StartDate AND @ EndDate GROUP BY room_type_id

Then test the equality :

SELECT (DATEDIFF(@EndDate, @StartDate) = Av_days )
 FROM
  (SELECT room_type_id, Count(*) as Av_days
  FROM this_table
   WHERE room_type_id=23 AND date BETWEEN @StartDate AND @ EndDate
  GROUP BY room_type_id) t

If you the same number of days, it will return 1 else 0

Answer 6

You need to use OR instead of AND. Your statement will only return a result if room 23 is equal to all 4 of those dates listed.

SELECT * FROM this_table 
WHERE room_type_id=23 
AND 
(
   date="2018-03-06 00:00:00" 
OR date="2018-03-07 00:00:00" 
OR date="2018-03-08 00:00:00" 
OR date="2018-03-09 00:00:00"
)