I am creating a database for table reservation system. Each table have it's own time slot list and I want to find available time slots for each table.
So I have the following tables:
time_slots table
----------------------------------
id || table_id || weekday || time
==================================
1 1 1 12:00
2 1 1 12:30
...
11 1 1 16:00
...
17 1 1 19:00
18 1 1 19:30
...
27 1 1 00:00
==================================
reservations table
-----------------------------------------------------------------
id || table_slot_id || start_date || end_date
=================================================================
1 1 2020-06-01 12:00:00 2020-06-01 12:20:00
2 1 2020-06-01 16:00:00 2020-06-01 19:00:00
=================================================================
I wrote query which allows to find all reserved time slots:
SELECT *
FROM table_slots, (SELECT *
FROM reservations
WHERE reservations.start_date::date = '2020-06-01'::date) as res
WHERE table_slots.weekday = extract(dow from '2020-06-01'::date)
AND table_slots.time BETWEEN res.start_date::time and res.end_date::time
ORDER BY table_slots.time
But I don't understand how to write query to find available time slots. So I expect that result should contain all time_slots where time is between 12:30 and 15:30; 19:30 and 00:00. How to do this?
Is it possible to write such queries with minimal overhead?
And the last question, is this good design for such systems? If not then what is the better designs in these scenerios.
Thanks!
You could use not exists. This would give you all available slots on June 1st:
select ts.*
from time_slots ts
where not exists (
select 1
from reservations r
where
r.table_slot_id = ts.id
and r.start_date >= '2020-06-01'::date
and r.start_date < '2020-07-01'::date
and r.start_date::time <= ts.time
and r.end_date::time > ts.time
)
Note that this assumes that reservations do not span across days.
It might be more efficient to express the where clause of the subquery as:
where
r.table_slot_id = ts.id
and r.start_date >= '2020-06-01'::date
and r.start_date <= '2020-06-01'::date + ts.time::interval
and r.end_date > '2020-06-01'::date + ts.time::interval
This would take advantage of an index on reservations(table_slot_id, start_date, end_date).
Related
I have two tables as follow:
position
--------------------------------
position_id description
17 team_lead
18 accountant
19 it_specialist
20 consultant
--------------------------------
assignment
------------------------------------------------------------
position_id people_id start stop
17 1001 2020-01-01 2021-06-01
17 1002 2021-06-01 2021-08-01
18 1003 2020-01-01 2021-12-01
19 1004 2020-01-01 2021-08-01
------------------------------------------------------------
I want to retrieve the positions that have no assignment today (2021-08-12), regardless if they had past assignments or not. The expected output should be:
position_id
17
19
20
How can I do this ? My attempts to use a left join like:
select
position.position_id
from position
left join assignment
on
assignment.position_id = position.position_id
where
/* incorrect. How to match a non-interval ? */
assignment.start >= DATE('now') or assignment.stop <= DATE('now')
fail to properly match what I want.
You can use not exists:
select p.*
from positions p
where not exists (select 1
from assignments a
where a.position_id = p.position_id and
a.start <= current_date and
a.stop >= current_date
);
It is not clear from your question is the stop date is included. That would affect the last comparison.
I have a table like shown below where I want to use the start and end date to evenly distribute the value for each row to the 3 months in each quarter to all of the quarters in between start and end date (last two columns).
I am familiar with generate series and intervals in Postgres but I am having hard time to get what I want.
My table has and ID column that groups rows together, a quarter column that indicates which quarter the row references for the ID, a value column that is the value for the whole quarter (and every quarter in the date range), and start_date and end_date columns indicating the date range. Here is a sample:
ID quarter value start_date end_date
1 2 152 2019-11-07 2050-12-30
1 1 785 2019-11-07 2050-12-30
2 2 152 2019-03-05 2050-12-30
2 1 785 2019-03-05 2050-12-30
3 4 41 2018-06-12 2050-12-30
3 3 50 2018-06-12 2050-12-30
3 2 88 2018-06-12 2050-12-30
3 1 29 2018-06-12 2050-12-30
4 2 1607 2018-12-17 2050-12-30
4 1 4803 2018-12-17 2050-12-30
Here is my desired output (for ID 1):
ID quarter value start_date end_date
1 2 152/3 2020-04-01 2020-07-01
1 1 785/3 2020-01-01 2020-04-01
1 2 152/3 2021-04-01 2021-07-01
1 1 785/3 2021-01-01 2021-04-01
start_date in the output will be the next quarter on first table. I need the series to be generated from the start_date to the end_date of the first table.
You can do this by using the GENERATE_SERIES function and passing in the start and end date for each unique (by ID) row and setting the interval to 3 months. Then join the result back with your original table on both ID and quarter.
Here's an example (note original_data is what I've called your first table):
WITH
quarters_table AS (
SELECT
t.ID,
(EXTRACT('month' FROM t.quarter_date) - 1)::INT / 3 + 1 AS quarter,
t.quarter_date::DATE AS start_date,
COALESCE(
LEAD(t.quarter_date) OVER (),
DATE_TRUNC('quarter', t.original_end_date) + INTERVAL '3 months'
)::DATE AS end_date
FROM (
SELECT
original_record.ID,
original_record.end_date AS original_end_date,
GENERATE_SERIES(
DATE_TRUNC('quarter', original_record.start_date),
DATE_TRUNC('quarter', original_record.end_date),
INTERVAL '3 months'
) AS quarter_date
FROM (
SELECT DISTINCT ON (original_data.ID)
original_data.ID,
original_data.start_date,
original_data.end_date
FROM
original_data
ORDER BY
original_data.ID
) AS original_record
) AS t
)
SELECT
quarters_table.ID,
quarters_table.quarter,
original_data.value::DOUBLE PRECISION / 3 AS value,
quarters_table.start_date,
quarters_table.end_date
FROM
quarters_table
INNER JOIN
original_data
ON
quarters_table.ID = original_data.ID
AND quarters_table.quarter = original_data.quarter;
Sample output:
id | quarter | value | start_date | end_date
----+---------+------------------+------------+------------
1 | 1 | 261.666666666667 | 2020-01-01 | 2020-04-01
1 | 2 | 50.6666666666667 | 2020-04-01 | 2020-07-01
1 | 1 | 261.666666666667 | 2021-01-01 | 2021-04-01
1 | 2 | 50.6666666666667 | 2021-04-01 | 2021-07-01
For completeness, here's the original_data table I've used in testing:
WITH
original_data AS (
SELECT
1 AS ID,
2 AS quarter,
152 AS value,
'2019-11-07'::DATE AS start_date,
'2050-12-30'::DATE AS end_date
UNION ALL
SELECT
1 AS ID,
1 AS quarter,
785 AS value,
'2019-11-07'::DATE AS start_date,
'2050-12-30'::DATE AS end_date
UNION ALL
SELECT
2 AS ID,
2 AS quarter,
152 AS value,
'2019-03-05'::DATE AS start_date,
'2050-12-30'::DATE AS end_date
-- ...
)
This is one way to go about it. Showing an example based on the output you've outlined. You can then add more conditions to the CASE/WHEN for additional quarters.
SELECT
ID,
Quarter,
Value/3 AS "Value",
CASE
WHEN Quarter = 1 THEN '2020-01-01'
WHEN Quarter = 2 THEN '2020-04-01'
END AS "Start_Date",
CASE
WHEN Quarter = 1 THEN '2020-04-01'
WHEN Quarter = 2 THEN '2020-07-01'
END AS "End_Date"
FROM
Table
I have created two tables one is "Timeclock" another is "Appointment" table. Time Clock table contains, for example,
12:00
12:05
12:10
12:15
12:20
12:25
12:30
12:35
12:40 etc...
Appointment Table.
When the appointment table contains records (Reservation)
Date: 2020-09-26 between From 12:10 to 12:15
Date: 2020-09-26 between From 12:20 to 12:30
Then the query result from the TimeClock table to be as follows,
12:00
12:05
12:35
12:40 etc...
When I run below query I get an error when the database contains more than 1 records but when DB contains 1 record then it works well. What is the solution?
SELECT Time24
FROM GlobalSetup.TimeClock
WHERE
Time24 not between
(SELECT start_time FROM Customer.Appointment WHERE start_date = '2020-09-26' and EmployeeRecID = 1)
and
(SELECT end_time FROM Customer.Appointment WHERE start_date = '2020-09-26' and EmployeeRecID = 1)
and Every5Mins = 1
Order By Time24
You seem to want times that are not between appointments. NOT EXISTS as suggested by GSerg is appropriate. I'm not sure why that answer was deleted.
I would write this as:
SELECT tc.Time24
FROM GlobalSetup.TimeClock tc
WHERE NOT EXISTS (SELECT 1
FROM Customer.Appointment a
WHERE a.EmployeeRecID = 1 AND
tc.Time24 >= a.start_time AND
tc.Time24 <= a.end_time
) AND
tc.Every5Mins = 1 AND
tc.Time24 >= '2020-09-26' AND
tc.Time24 < '2020-09-27'
ORDER BY Time24;
The above assumes that the start and end times include the date. If that is not true, then an additional comparison is needed:
SELECT tc.Time24
FROM GlobalSetup.TimeClock tc
WHERE NOT EXISTS (SELECT 1
FROM Customer.Appointment a
WHERE a.EmployeeRecID = 1 AND
a.start_date = '2020-09-26' AND
tc.Time24 >= a.start_time AND
tc.Time24 <= a.end_time
) AND
tc.Every5Mins = 1 AND
tc.Time24 >= '2020-09-26' AND
tc.Time24 < '2020-09-27'
ORDER BY Time24;
I'm facing a challenging task here, spent a day on it and I was only able to solve it through a procedure but it is taking too long to run for all projects.
I would like to solve it in a single query if possible (no functions or procedures).
There is already some questions here doing it in programming languages OR sql functions/procedures (Wich I also solved min). So I'm asking if it is possible to solve it with just SQL
The background info is:
A project table
A phase table
A holiday table
A dayexception table which cancel a holiday or a weekend day (make that date as a working day) and it is associated with a project
A project may have 0-N phases
A phase have a start date, a duration and a draworder (needed by the system)
Working days is all days that is not weekend days and not a holiday (exception is if that date is in dayexception table)
Consider this following scenario:
project | phase(s) | Dayexception | Holiday
id | id pid start duration draworder | pid date | date
1 | 1 1 2014-01-20 10 0 | 1 2014-01-25 | 2014-01-25
| 2 1 2014-02-17 14 2 | |
The ENDDATE for the project id 1 and phase id 1 is actually 2014-01-31 see the generated data below:
The date on the below data (and now on) is formatted as dd/mm/yyyy (Brazil format) and the value N is null
proj pha start day weekday dayexcp holiday workday
1 1 20/01/2014 20/01/2014 2 N N 1
1 1 20/01/2014 21/01/2014 3 N N 1
1 1 20/01/2014 22/01/2014 4 N N 1
1 1 20/01/2014 23/01/2014 5 N N 1
1 1 20/01/2014 24/01/2014 6 N N 1
1 1 20/01/2014 25/01/2014 7 25/01/2014 25/01/2014 1
1 1 20/01/2014 26/01/2014 1 N N 0
1 1 20/01/2014 27/01/2014 2 N 27/01/2014 0
1 1 20/01/2014 28/01/2014 3 N N 1
1 1 20/01/2014 29/01/2014 4 N N 1
To generate the above data I created a view daysOfYear with all days from 2014 and 2015 (it can be bigger or smaller, created it with two years for the year turn cases) with a CTE query if you guys want to see it let me know and I will add it here. And the following select statement:
select ph.project_id proj,
ph.id phase_id pha,
ph.start,
dy.curday day,
dy.weekday, /*weekday here is a calling to the weekday function of db2*/
doe.exceptiondate dayexcp,
h.date holiday,
case when exceptiondate is not null or (weekday not in (1,7) and h.date is null)
then 1 else 0 end as workday
from phase ph
inner join daysofyear dy
on (year(ph.start) = dy.year)
left join dayexception doe
on (ph.project_id = doe.project_id
and dy.curday = truncate(doe.exceptiondate))
left join holiday h
on (dy.curday = truncate(h.date))
where ph.project_id = 1
and ph.id = 1
and dy.year in (year(ph.start),year(ph.start)+1)
and dy.curday>=ph.start
and dy.curday<=ph.start + ((duration - 1) days)
order by ph.project_id, start, dy.curday, draworder
To solve this scenario I created the following query:
select project_id,
min(start),
max(day) + sum(case when workday=0 then 1 else 0 end) days as enddate
from project_phase_days /*(view to the above select)*/
This will return correctly:
proj start enddate
1 20/01/2014 31/01/2014
The problem I couldn't solve is if the days I'm adding (non workdays sum(case when workday=0 then 1 else 0 end) days ) to the last enddate (max(day)) is weekend days or holidays or exceptions.
See the following scenario (The duration for the below phase is 7):
proj pha start day weekday dayexcp holiday workday
81 578 14/04/2014 14/04/2014 2 N N 1
81 578 14/04/2014 15/04/2014 3 N N 1
81 578 14/04/2014 16/04/2014 4 N N 1
81 578 14/04/2014 17/04/2014 5 N N 1
81 578 14/04/2014 18/04/2014 6 N 18/04/2014 0
81 578 14/04/2014 19/04/2014 7 N 0
81 578 14/04/2014 20/04/2014 1 N 20/04/2014 0
/*the below data I added to show the problem*/
81 578 14/04/2014 21/04/2014 2 N 21/04/2014 0
81 578 14/04/2014 22/04/2014 3 N 1
81 578 14/04/2014 23/04/2014 4 N 1
81 578 14/04/2014 24/04/2014 5 N 1
With the above data my query will return
proj start enddate
81 14/04/2014 23/04/2014
But the correct result would be the enddate as 24/04/2014 that's because my query doesn't take into account if the days after the last day is weekend days or holidays (or exceptions for that matter) as you can see in the dataset above the day 21/04/2014 which is outside my duration is also a Holiday.
I also tried to create a CTE on phase table to add a day for each iteration until the duration is over but I couldn't add the exceptions nor the holidays because the DB2 won't let me add a left join on the CTE recursion. Like this:
with CTE (projectid, start, enddate, duration, level) as (
select projectid, start, start as enddate, duration, 1
from phase
where project_id=1
and phase_id=1
UNION ALL
select projectid, start, enddate + (level days), duration,
case when isWorkDay(enddate + (level days)) then level+1 else level end as level
from CTE left join dayexception on ...
left join holiday on ...
where level < duration
) select * from CTE
PS: the above query doesn't work because of the DB2 limitations and isWorkDay is just as example (it would be a case on the dayexception and holiday table values).
If you have any doubts, please just ask in the comments.
Any help would be greatly appreciated. Thanks.
How to count business days forward and backwards.
Background last Century I worked at this company that used this technique. So this is a pseudo code answer. It worked great for their purposes.
What you need is a table that contains a date column and and id column that increments by one. Fill the table with only business dates... That's the tricky part because of the observing date on another date. Like 2017-01-02 was a holiday where I work but its not really a recognized holiday AFAIK.
How to get 200 business days in the future.
Select the min(id) where date >= to current date.
Select the date where id=id+200.
How to get 200 business days in the past.
Select the min(id) from table with a date >= to current date.
Select the date with id=id-200.
Business days between.
select count(*) from myBusinessDays where "date" between startdate and enddate
Good Luck as this is pseudo code.
So, using the idea of #danny117 answer I was able to create a query to solve my problem. Not exactly his idea but it gave me directions to solve it, so I will mark it as the correct answer and this answer is to share the actual code to solve it.
First let me share the view I created to the periods. As I said I created a view daysofyear with the data of 2014 and 2015 (in my final solution I added a considerable bigger interval without impacting in the end result). Ps: the date format here is in Brazil format dd/mm/yyyy
create or replace view daysofyear as
with CTE (curday, year, weekday) as (
select a1.firstday, year(a1.firstday), dayofweek(a1.firstday)
from (select to_date('01/01/1990', 'dd/mm/yyyy') firstday
from sysibm.sysdummy1) as a1
union all
select a.curday + 1 day as sumday,
year(a.curday + 1 day),
dayofweek(a.curday + 1 day)
from CTE a
where a.curday < to_date('31/12/2050', 'dd/mm/yyyy')
)
select * from cte;
With that View I then created another view with the query on my question adding an amount of days based on my historical data (bigger phase + a considerable margin) here it is:
create or replace view project_phase_days as
select ph.project_id proj,
ph.id phase_id pha,
ph.start,
dy.curday day,
dy.weekday, /*weekday here is a calling to the weekday function of db2*/
doe.exceptiondate dayexcp,
h.date holiday,
ph.duration,
case when exceptiondate is not null or (weekday not in (1,7) and h.date is null)
then 1 else 0 end as workday
from phase ph
inner join daysofyear dy
on (year(ph.start) = dy.year)
left join dayexception doe
on (ph.project_id = doe.project_id
and dy.curday = truncate(doe.exceptiondate))
left join holiday h
on (dy.curday = truncate(h.date))
where dy.year in (year(ph.start),year(ph.start)+1)
and dy.curday>=ph.start
and dy.curday<=ph.start + ((duration - 1) days) + 200 days
/*max duration in database is 110*/
After that I then created this query:
select p.id,
a.start,
a.curday as enddate
from project p left join
(
select p1.project_id,
p1.duration,
p1.start,
p1.curday,
row_number() over (partition by p1.project_id
order by p1.project_id, p1.start, p1.curday) rorder
from project_phase_days p1
where p1.validday=1
) as a
on (p.id = a.project_id
and a.rorder = a.duration)
order by p.id, a.start
What it does is select all workdays from my view (joined with my other days view) rownumber based on the project_id ordered by project_id, start date and current day (curday) I then join with the project table to get the trick part that solved the problem which is a.rorder = a.duration
If you guys need more explanation I will be glad to provide.
I have a problem. I need to get the date difference in terms of hours in my table but the problem is it is saved in the same field. This is my table would look like.
RecNo. Employeeno recorddate recordtime recordval
1 001 8/22/2014 8:15 AM 1
2 001 8/22/2014 5:00 PM 2
3 001 8/24/2014 8:01 AM 1
4 001 8/24/2014 5:01 PM 2
1 indicates time in and 2 indicates time out. Now, How will i get the number of hours worked for each day? What i want to get is something like this.
Date hoursworked
8/22/2014 8
8/24/2014 8
I am using VS 2010 and SQL server 2005
You could self-join each "in" record with its corresponding "out" record and use datediff to subtract them:
SELECT time_in.employeeno AS "Employee No",
time_in.recorddate AS "Date",
DATEDIFF (hour, time_in.recordtime, time_out.recordtime)
AS "Hours Worked"
FROM (SELECT *
FROM my_table
WHERE recordval = 1) time_in
INNER JOIN (SELECT *
FROM my_table
WHERE recordval = 2) time_out
ON time_in.employeeno = time_out.employeeno AND
time_in.recorddate = time_out.recorddate
If you always record time in and time out for every employee, and just one per day, using a self-join should work:
SELECT
t1.Employeeno,
t1.recorddate,
t1.recordtime AS [TimeIn],
t2.recordtime AS [TimeOut],
DATEDIFF(HOUR,t1.recordtime, t2.recordtime) AS [HoursWorked]
FROM Table1 t1
INNER JOIN Table1 t2 ON
t1.Employeeno = t2.Employeeno
AND t1.recorddate = t2.recorddate
WHERE t1.recordval = 1 AND t2.recordval = 2
I included the recordtime fields as time in, time out, if you don't want them just remove them.
Note that this datediff calculation gives 9 hours, and not 8 as you suggested.
Sample SQL Fiddle
Using this sample data:
with table1 as (
select * from ( values
(1,'001', cast('20140822' as datetime),cast('08:15:00 am' as time),1)
,(2,'001', cast('20140822' as datetime),cast('05:00:00 pm' as time),2)
,(3,'001', cast('20140824' as datetime),cast('08:01:00 am' as time),1)
,(4,'001', cast('20140824' as datetime),cast('04:59:00 pm' as time),2)
,(5,'001', cast('20140825' as datetime),cast('10:01:00 pm' as time),1)
,(6,'001', cast('20140826' as datetime),cast('05:59:00 am' as time),2)
)data(RecNo,EmployeeNo,recordDate,recordTime,recordVal)
)
this query
SELECT
Employeeno
,convert(char(10),recorddate,120) as DateStart
,convert(char(5),cast(TimeIn as time)) as TimeIn
,convert(char(5),cast(TimeOut as time)) as TimeOut
,DATEDIFF(minute,timeIn, timeOut) / 60 AS [HoursWorked]
,DATEDIFF(minute,timeIn, timeOut) % 60 AS [MinutesWorked]
FROM (
SELECT
tIn.Employeeno,
tIn.recorddate,
dateadd(minute, datediff(minute,0,tIn.recordTime), tIn.recordDate)
as TimeIn,
( SELECT TOP 1
dateadd(minute, datediff(minute,0,tOut.recordTime), tOut.recordDate)
as TimeOut
FROM Table1 tOut
WHERE tOut.RecordVal = 2
AND tOut.EmployeeNo = tIn.EmployeeNo
AND tOut.RecNo > tIn.RecNo
ORDER BY tOut.EmployeeNo, tOut.RecNo
) as TimeOut
FROM Table1 tIn
WHERE tIn.recordval = 1
) T
yields (as desired)
Employeeno DateStart TimeIn TimeOut HoursWorked MinutesWorked
---------- ---------- ------ ------- ----------- -------------
001 2014-08-22 08:15 17:00 8 45
001 2014-08-24 08:01 16:59 8 58
001 2014-08-25 22:01 05:59 7 58
No assumptions are made about shifts not running across midnight (see case 3).
This particular implementation may not be the most performant way to construct this correlated subquery, so if there is a performance problem come back and we can look at it again. However running those tests requires a large dataset which I don't feel like constructing just now.