I have a large data table in PostgreSQL containing, among other information, a column for start date and end date. For each row, I am hoping to tally the number of other rows in the same table which contain an overlapping date range and create a new table with these values.
To calculate overlapping date range, I had been planning to use:
where (start_date between [target_start_date] and [target_end_date]) or
(end_date between [target_start_date] and [target_end_date]))
But I have no idea how to do this for each row while comparing to its own table and tallying a count of times this condition is met.
Any ideas would be greatly appreciated, thank you!
One possibility is to use a subquery and the OVERLAPS operator.
SELECT t1.*,
(SELECT count(*)
FROM elbat t2
WHERE (t2.target_start_date,
t2.target_end_date) OVERLAPS (t1.target_start_date,
t1.target_end_date))
FROM elbat t1;
Related
I have a table in Postgres 14.2
Table name is test
There are 3 columns: date, high, and five_day_mavg (date is PK if it matters)
I have a select statement which properly calculates a 5 day moving average based on the data in high.
select date,
avg(high) over (order by date rows between 4 preceding and current row) as mavg_calc
from test
It products output as such:
I have 2 goals:
First to store the output of the query in five_day_mavg.
Second to store this in such a way that when I a new row with data
in high, it automatically calculates that value
The closest I got was:
update test set five_day_mavg = a.mav_calc
from (
select date,
avg(high) over (order by date rows between 4 preceding and current row) as mav_calc
from test
) a;
but all that does is sets the value of every row in five_day_mavg to entire average of high
Thanks to #a_horse_with_no_name
I played around with the WHERE clause
update test l set five_day_mavg = b.five_day_mavg from (select date, avg(high) over (order by date rows between 4 preceding and current row) as five_day_mavg from test )b where l.date = b.date;
a couple of things. I defined each table. The original table I aliased as l, the temporary table created by doing a windows function (the select statement in parenthesis) I aliased as b and I joined with the WHERE clause on date which is the index/primary key.
Also, I was using 'a' as the letter for alias, and I think that may have contributed to the issue.
Either way, solved now.
I have a calendar table called CalendarInformation that gives me a list of dates from 2015 to 2025. This table has a column called BusinessDay that shows what dates are weekends or holidays. I have another table called OpenProblemtimeDiffTable with a column called number for my problem number and a date for when the problem was opened called ProblemNew and another date for the current column called Now. What I want to do is for each problem number grab its date ranges and find the dates between and then sum them up to give me the number of business days. Then I want to insert these values in another table with the problem number associated with the business day.
Thanks in advance and I hope I was clear.
TRUNCATE TABLE ProblemsMoreThan7BusinessDays
DECLARE #date AS date
DECLARE #businessday AS INT
DECLARE #Startdate as DATE, #EndDate as DATE
DECLARE CONTACT_CURSOR CURSOR FOR
SELECT date, businessday
FROM CalendarInformation
OPEN contact_cursor
FETCH NEXT FROM Contact_cursor INTO #date, #businessday
WHILE (##FETCH_STATUS=0)
BEGIN
SELECT #enddate= now FROM OpenProblemtimeDiffTable
SELECT #Startdate= problemnew FROM OpenProblemtimeDiffTable
SET #Date=#Startdate
PRINT #enddate
PRINT #startdate
SELECT #businessday= SUM (businessday) FROM CalendarInformation WHERE date > #startdate AND date <= #Enddate
INSERT INTO ProblemsMoreThan7BusinessDays (businessdays, number)
SELECT #businessday, number
FROM OpenProblemtimeDiffTable
FETCH NEXT FROM CONTACT_CURSOR INTO #date, #businessday
END
CLOSE CONTACT_CURSOR
DEALLOCATE CONTACT_CURSOR
I tried this code using a cursor and I'm close, but I cannot get the date ranges to change for each row.
So if I have a problemnumber with date ranges between 02-07-2018 and 05-20-2019, I would want in my new table the sum of business days from the calendar along with the problem number. So my output would be column number PROB0421 businessdays (with the correct sum). Then the next problem PRB0422 with date ranges of 11-6-18 to 5-20-19. So my output would be PROB0422 with the correct sum of business days.
Rather than doing this in with a cursor, you should approach this in a set based manner. That you already have a calendar table makes this a lot easier. The basic approach is to select from your data table and join into your calendar table to return all the rows in the calendar table that sit within your date range. From here you can then aggregate as you require.
This would look something like the below, though apply it to your situation and adjust as required:
select p.ProblemNow
,p.Now
,sum(c.BusinessDay) as BusinessDays
from dbo.Problems as p
join dbo.calendar as c
on c.CalendarDate between p.ProblemNow and p.Now
and c.BusinessDay = 1
group by p.ProblemNow
,p.Now
I think you can do this without a cursor. Should only require a single insert..select statement.
I assume your "businessday" column is just a bit or flag-type field that is 1 if the date is a business day and 0 if not? If so, this should work (or something close to it if I'm not understanding your environment properly).:
insert ProblemsMoreThan7BusinessDays
(
businessdays
, number
)
select
number
, sum( businessday ) -- or count(*)
from OpenProblemtimeDiffTable op
inner join CalendarInformation ci on op.problem_new >= ci.[date]
and op.[now] <= ci.[date]
and ci.businessday = 1
group by
problem_number
I usually try to avoid the use of cursors and working with data in a procedural manner, especially if I can handle the task as above. Dont think of the data as 1000's of individual rows, but think of the data as only two sets of data. How do they relate?
I have two tables with IDs and time stamps. Table 1 has two columns: ID and created_at. Table 2 has two columns: ID and post_date. I'd like to create a chart in Tableau that displays the Number of Records in Table 1 divided by Number of Records in Table 2, by week. How can I achieve this?
One way might be to use Custom SQL like this to create a new data source for your visualization:
SELECT created_table.created_date,
created_table.created_count,
posted_table.posted_count
FROM (SELECT TRUNC (created_at) AS created_date, COUNT (*) AS created_count
FROM Table1) created_table
LEFT JOIN
(SELECT TRUNC (post_date) AS posted_date, COUNT (*) AS posted_count
FROM Table2) posted_table
ON created_table.created_date = posted_table.posted_date
This would give you dates and counts from both tables for those dates, which you could group using Tableau's date functions in the visualization. I made created_table the first part of the left join on the assumption that some records would be created and not posted, but you wouldn't have posts without creations. If that isn't the case you will want a different join.
I need to sum values that are + 2 months or within a quarter period (related date table)
is there a way to use dense rank to partition those periods (custom periods)?
select
FiscalMonth
,Value
from table
The sql will have to do the following:
Join the value table and the period table
Include the period in the select list and sum the value, grouping by the period
i.e
select b.period, sum(a.value)
from table a
inner join period b on a.FiscalMonth between b.StartMonth and b.EndMonth
group by b.period
Note: The join condition will have to be modified based on what data you actually have in the period table.
Hope this helps
Well, If you need value from an X interval, by month you could use something like:
SELECT *
FROM yourTable
MONTH(some_date) = MONTH(CURRENT_DATE - INTERVAL 1 MONTH) //Could be X interval!
This is an example (which show the results of the previous month, from the actual one). Just trying to write that it is possible to massage the query in functions on intervals.
Of course, you could use the SUMcommand for the adding.
I have two tables, table1 and table2, both of which contain columns that store postgis geometries. What I want to do is see where the geometry stored in any row of table2 geometrically intersects with the geometry stored in any row of table1 and update a count column in table1 with the number of intersections. Therefore, if I have a geometry in row 1 of table1 that intersects with the geometries stored in 5 rows in table2, I want to store a count of 5 in a separate column in table one. The tricky part for me is that I want to do this for every row of column 1 at the same time.
I have the following:
UPDATE circles SET intersectCount = intersectCount + 1 FROM rectangles
WHERE ST_INTERSECTS(cirlces.geom, rectangles.geom);
...which doesn't seem to be working. I'm not too familiar with postgres (or sql in general) and I'm wondering if I can do this all in one statement or if I need a few. I have some ideas for how I would do this with multiple statements (or using for loop) but I'm really looking for a concise solution. Any help would be much appreciated.
Thanks!
something like:
update t1 set ctr=helper.ctr
from (
select t1.id, count(*) as cnt
from t1, t2
where st_intersects(t1.col, t2.col)
group by t1.id
) helper
where helper.id=t1.id
?
btw: Your version does not work, because a row can get updated only once in a single update statement.