Unable to Calculate 7 Day Moving Average due to inconsistent dates - postgresql

I just noticed that my code below is not actually a 7 day moving avg, and instead it is a 7 row moving avg. The dates in my table spans several months and I am trying to iron out since I have inconsistent data flow so I can't expect the last 7 rows of the window function to actually represent a 7 day avg. Thanks.
select date, sales,
avg(sales) over(order by date rows between 6 preceding and current row)
from sales_info
order by date


You can get a bit closer to a true 7 day moving average by using RANGE instead of ROWS for your range specification.
Read more about window function frames here.
I believe this should work for you:
select date, sales,
avg(sales) over(order by date range between '6 days' preceding and current row)
from sales_info
order by date;
Here's a demonstration with made up data:
SELECT i,
t,
avg(i) OVER (ORDER BY t RANGE BETWEEN '6 days' preceding and current row) FROM (
SELECT i, t
FROM generate_series('2021-01-01'::timestamp, '2021-02-01'::timestamp, '1 day') WITH ORDINALITY as g(t, i)
) sub;
i | t | avg
----+---------------------+------------------------
1 | 2021-01-01 00:00:00 | 1.00000000000000000000
2 | 2021-01-02 00:00:00 | 1.5000000000000000
3 | 2021-01-03 00:00:00 | 2.0000000000000000
4 | 2021-01-04 00:00:00 | 2.5000000000000000
5 | 2021-01-05 00:00:00 | 3.0000000000000000
6 | 2021-01-06 00:00:00 | 3.5000000000000000
7 | 2021-01-07 00:00:00 | 4.0000000000000000
8 | 2021-01-08 00:00:00 | 5.0000000000000000
9 | 2021-01-09 00:00:00 | 6.0000000000000000
10 | 2021-01-10 00:00:00 | 7.0000000000000000
11 | 2021-01-11 00:00:00 | 8.0000000000000000
12 | 2021-01-12 00:00:00 | 9.0000000000000000
13 | 2021-01-13 00:00:00 | 10.0000000000000000
14 | 2021-01-14 00:00:00 | 11.0000000000000000
15 | 2021-01-15 00:00:00 | 12.0000000000000000
16 | 2021-01-16 00:00:00 | 13.0000000000000000
17 | 2021-01-17 00:00:00 | 14.0000000000000000
18 | 2021-01-18 00:00:00 | 15.0000000000000000
19 | 2021-01-19 00:00:00 | 16.0000000000000000
20 | 2021-01-20 00:00:00 | 17.0000000000000000
21 | 2021-01-21 00:00:00 | 18.0000000000000000
22 | 2021-01-22 00:00:00 | 19.0000000000000000
23 | 2021-01-23 00:00:00 | 20.0000000000000000
24 | 2021-01-24 00:00:00 | 21.0000000000000000
25 | 2021-01-25 00:00:00 | 22.0000000000000000
26 | 2021-01-26 00:00:00 | 23.0000000000000000
27 | 2021-01-27 00:00:00 | 24.0000000000000000
28 | 2021-01-28 00:00:00 | 25.0000000000000000
29 | 2021-01-29 00:00:00 | 26.0000000000000000
30 | 2021-01-30 00:00:00 | 27.0000000000000000
31 | 2021-01-31 00:00:00 | 28.0000000000000000
32 | 2021-02-01 00:00:00 | 29.0000000000000000

Related

Postgres max value per hour with time it occurred

Given a Postgres table with columns highwater_datetime::timestamp and highwater::integer, I am trying to construct a select statement for a given highwater_datetime range, that generates rows with a column for the max highwater for each hour (first occurrence when dups) and another column showing the highwater_datetime when it occurred (truncated to the minute and order by highwater_datetime asc). e.g.
| highwater_datetime | max_highwater |
+--------------------+---------------+
| 2021-01-27 20:05 | 8 |
| 2021-01-27 21:00 | 7 |
| 2021-01-27 22:00 | 7 |
| 2021-01-27 23:00 | 7 |
| 2021-01-28 00:00 | 7 |
| 2021-01-28 01:32 | 7 |
| 2021-01-28 02:00 | 7 |
| 2021-01-28 03:00 | 7 |
| 2021-01-28 04:22 | 9 |

DISTINCT ON should do the trick:
SELECT DISTINCT ON (date_trunc('hour', highwater_datetime))
highwater_datetime,
highwater
FROM mytable
ORDER BY date_trunc('hour', highwater_datetime),
highwater DESC,
highwater_datetime;
DISTINCT ON will output the first row for each entry with the same hour according to the ORDER BY clause.

Take data for each day in tsrange

Assuming a have table like
+----------------------------+-----+-----------+
+ tsrange + id + anyvalues +
+----------------------------------------------+
+["2019-09-20","2019-09-25") + 1 + ... +
+["2019-09-01","2019-09-23") + 2 + ... +
+["2019-09-15","2019-09-22") + 3 + ... +
+ ... + ... + ... +
+----------------------------+-----+-----------+
Is it possible to get data state for each day from 2019-09-01 till 2019-09-25?
I just have no idea what could be query or probably any function exists for it purpose.
So in output i'd like to get 25 raws with values for each id (if it exists for it)

I think you are looking for something like this? The expected output would help determine if this is correct:
select d, count(id)
FROM YOUR_TABLE
RIGHT JOIN generate_series('2019-09-01'::timestamp, '2019-09-25'::timestamp, interval '1 day') AS g(d) on tsrange #> d
group by d order by 1;
d | count
---------------------+-------
2019-09-01 00:00:00 | 1
2019-09-02 00:00:00 | 1
2019-09-03 00:00:00 | 1
2019-09-04 00:00:00 | 1
2019-09-05 00:00:00 | 1
2019-09-06 00:00:00 | 1
2019-09-07 00:00:00 | 1
2019-09-08 00:00:00 | 1
2019-09-09 00:00:00 | 1
2019-09-10 00:00:00 | 1
2019-09-11 00:00:00 | 1
2019-09-12 00:00:00 | 1
2019-09-13 00:00:00 | 1
2019-09-14 00:00:00 | 1
2019-09-15 00:00:00 | 2
2019-09-16 00:00:00 | 2
2019-09-17 00:00:00 | 2
2019-09-18 00:00:00 | 2
2019-09-19 00:00:00 | 2
2019-09-20 00:00:00 | 3
2019-09-21 00:00:00 | 3
2019-09-22 00:00:00 | 2
2019-09-23 00:00:00 | 1
2019-09-24 00:00:00 | 1
2019-09-25 00:00:00 | 0
(25 rows)

Finding the next occurrence of particular day of the week

How can I take a datetime column start_at convert it to a day of week and find out the next future occurrence relative to the current date?
Here I'm trying to add the DOW to the current week but it doesn't appear to be correct.
SELECT date_trunc('week', current_date) + CAST(extract(dow from start_at) || ' days' AS interval)
Full example:
SELECT id event_id,
GENERATE_SERIES(date_trunc('week', current_date) + CAST(extract(dow from start_at) + 1 || ' days' AS interval) + start_at::time, current_date + interval '3 weeks', '1 week'::INTERVAL) AS start_at
FROM events
Events
+-----+---------------------------+---------------------+
| id | start_at | recurring_schedule |
+-----+---------------------------+---------------------+
| 358 | 2015-01-23 20:00:00 +0000 | Weekly |
| 359 | 2016-01-22 19:30:00 +1100 | Monthly |
| 360 | 2016-02-01 19:00:00 +1100 | Weekly |
| 361 | 2016-02-01 20:00:00 +0000 | Weekly |
| 362 | 2014-02-13 20:00:00 +0000 | Bi-Weekly |
+-----+---------------------------+---------------------+
Output
+----------+---------------------------+
| event_id | start_at |
+----------+---------------------------+
| 35 | 2018-04-11 19:30:00 +0000 |
| 94 | 2018-04-12 20:00:00 +0100 |
| 269 | 2018-04-13 18:30:00 +0100 |
| 45 | 2018-04-13 20:00:00 +0100 |
| 242 | 2018-04-13 19:30:00 +1100 |
| 35 | 2018-04-18 19:30:00 +0000 |
| 94 | 2018-04-19 20:00:00 +0100 |
| 269 | 2018-04-20 18:30:00 +0100 |
| 45 | 2018-04-20 20:00:00 +0100 |
| 242 | 2018-04-20 19:30:00 +1100 |
+----------+---------------------------+

Give this a try:
SELECT id event_id,
GENERATE_SERIES(date_trunc('week', current_date)::date
+ (extract(isodow from start_at)::int - 1) + start_at::time, current_date
+ interval '3 weeks', '1 week'::INTERVAL) AS start_at
FROM events

Window function to achieve running sum that resets in Postgres SQL [duplicate]

I wrote a query that creates two columns: the_day, and the amount_raised on that day. Here is what I have:
And I would like to add a column that has a running sum of amount_raised:
Ultimately, I would like the sum column to reset after it reaches 1 million.
The recursive approach is above my pay grade, so if anyone knows a way to reset the sum without creating an entirely new table, please comment (maybe with a RESET function?). Thank you

I'd like to thank Juan Carlos Oropeza for providing a script and SQLFiddle with the test data. George, you should have done that.
The query itself it rather simple.
At first calculate a simple running sum (CTE_RunningSum) and divide it by 1,000,000 to get number of whole millions.
Then calculate the running sum again with partitioning by the number of millions.
SQL Fiddle
I included the columns RunningSum and Millions in the final result to illustrate how the query works.
WITH
CTE_RunningSum
AS
(
SELECT
ID
,day_t
,collect
,SUM(collect) OVER(ORDER BY day_t, id) AS RunningSum
,(SUM(collect) OVER(ORDER BY day_t, id)) / 1000000 AS Millions
FROM myTable
)
SELECT
ID
,day_t
,collect
,RunningSum
,Millions
,SUM(collect) OVER(PARTITION BY Millions ORDER BY day_t, id) AS Result
FROM CTE_RunningSum
ORDER BY day_t, id;
Result
| id | day_t | collect | runningsum | millions | result |
|-----|-----------------------------|---------|------------|----------|---------|
| 90 | March, 11 2015 00:00:00 | 69880 | 69880 | 0 | 69880 |
| 13 | March, 25 2015 00:00:00 | 69484 | 139364 | 0 | 139364 |
| 49 | March, 27 2015 00:00:00 | 57412 | 196776 | 0 | 196776 |
| 41 | March, 30 2015 00:00:00 | 56404 | 253180 | 0 | 253180 |
| 99 | April, 03 2015 00:00:00 | 59426 | 312606 | 0 | 312606 |
| 1 | April, 10 2015 00:00:00 | 65825 | 378431 | 0 | 378431 |
| 100 | April, 27 2015 00:00:00 | 60884 | 439315 | 0 | 439315 |
| 50 | May, 11 2015 00:00:00 | 39641 | 478956 | 0 | 478956 |
| 58 | May, 11 2015 00:00:00 | 49759 | 528715 | 0 | 528715 |
| 51 | May, 17 2015 00:00:00 | 32895 | 561610 | 0 | 561610 |
| 15 | May, 19 2015 00:00:00 | 50847 | 612457 | 0 | 612457 |
| 66 | May, 29 2015 00:00:00 | 66332 | 678789 | 0 | 678789 |
| 4 | June, 04 2015 00:00:00 | 46891 | 725680 | 0 | 725680 |
| 38 | June, 09 2015 00:00:00 | 64732 | 790412 | 0 | 790412 |
| 79 | June, 14 2015 00:00:00 | 62843 | 853255 | 0 | 853255 |
| 37 | June, 28 2015 00:00:00 | 54315 | 907570 | 0 | 907570 |
| 59 | June, 30 2015 00:00:00 | 34885 | 942455 | 0 | 942455 |
| 71 | July, 08 2015 00:00:00 | 46440 | 988895 | 0 | 988895 |
| 31 | July, 10 2015 00:00:00 | 39649 | 1028544 | 1 | 39649 |
| 91 | July, 12 2015 00:00:00 | 65048 | 1093592 | 1 | 104697 |
| 57 | July, 14 2015 00:00:00 | 60394 | 1153986 | 1 | 165091 |
| 98 | July, 20 2015 00:00:00 | 34481 | 1188467 | 1 | 199572 |
| 3 | July, 26 2015 00:00:00 | 58672 | 1247139 | 1 | 258244 |
| 95 | August, 19 2015 00:00:00 | 52393 | 1299532 | 1 | 310637 |
| 74 | August, 20 2015 00:00:00 | 37972 | 1337504 | 1 | 348609 |
| 20 | August, 27 2015 00:00:00 | 36882 | 1374386 | 1 | 385491 |
| 2 | September, 07 2015 00:00:00 | 39408 | 1413794 | 1 | 424899 |
| 14 | September, 09 2015 00:00:00 | 40234 | 1454028 | 1 | 465133 |
| 6 | September, 17 2015 00:00:00 | 65957 | 1519985 | 1 | 531090 |
| 93 | September, 29 2015 00:00:00 | 47213 | 1567198 | 1 | 578303 |
| 35 | September, 30 2015 00:00:00 | 49446 | 1616644 | 1 | 627749 |
| 86 | October, 11 2015 00:00:00 | 34291 | 1650935 | 1 | 662040 |
| 75 | October, 12 2015 00:00:00 | 31448 | 1682383 | 1 | 693488 |
| 19 | October, 14 2015 00:00:00 | 48509 | 1730892 | 1 | 741997 |
| 56 | October, 26 2015 00:00:00 | 30072 | 1760964 | 1 | 772069 |
| 48 | October, 28 2015 00:00:00 | 58527 | 1819491 | 1 | 830596 |
| 40 | November, 05 2015 00:00:00 | 67293 | 1886784 | 1 | 897889 |
| 33 | November, 09 2015 00:00:00 | 41944 | 1928728 | 1 | 939833 |
| 34 | November, 11 2015 00:00:00 | 35516 | 1964244 | 1 | 975349 |
| 85 | November, 20 2015 00:00:00 | 43920 | 2008164 | 2 | 43920 |
| 18 | November, 23 2015 00:00:00 | 44925 | 2053089 | 2 | 88845 |
| 62 | December, 24 2015 00:00:00 | 34678 | 2087767 | 2 | 123523 |
| 67 | December, 25 2015 00:00:00 | 35323 | 2123090 | 2 | 158846 |
| 81 | December, 28 2015 00:00:00 | 37071 | 2160161 | 2 | 195917 |
| 54 | January, 02 2016 00:00:00 | 32330 | 2192491 | 2 | 228247 |
| 70 | January, 06 2016 00:00:00 | 47875 | 2240366 | 2 | 276122 |
| 28 | January, 23 2016 00:00:00 | 40250 | 2280616 | 2 | 316372 |
| 65 | January, 25 2016 00:00:00 | 49404 | 2330020 | 2 | 365776 |
| 73 | January, 26 2016 00:00:00 | 65879 | 2395899 | 2 | 431655 |
| 5 | February, 05 2016 00:00:00 | 53953 | 2449852 | 2 | 485608 |
| 32 | February, 11 2016 00:00:00 | 44988 | 2494840 | 2 | 530596 |
| 53 | February, 25 2016 00:00:00 | 68948 | 2563788 | 2 | 599544 |
| 83 | March, 11 2016 00:00:00 | 47244 | 2611032 | 2 | 646788 |
| 8 | March, 25 2016 00:00:00 | 51809 | 2662841 | 2 | 698597 |
| 82 | March, 25 2016 00:00:00 | 66506 | 2729347 | 2 | 765103 |
| 88 | April, 06 2016 00:00:00 | 69288 | 2798635 | 2 | 834391 |
| 89 | April, 14 2016 00:00:00 | 43162 | 2841797 | 2 | 877553 |
| 52 | April, 23 2016 00:00:00 | 47772 | 2889569 | 2 | 925325 |
| 7 | April, 27 2016 00:00:00 | 33368 | 2922937 | 2 | 958693 |
| 84 | April, 27 2016 00:00:00 | 57644 | 2980581 | 2 | 1016337 |
| 17 | May, 17 2016 00:00:00 | 35416 | 3015997 | 3 | 35416 |
| 61 | May, 17 2016 00:00:00 | 64603 | 3080600 | 3 | 100019 |
| 87 | June, 07 2016 00:00:00 | 41865 | 3122465 | 3 | 141884 |
| 97 | June, 08 2016 00:00:00 | 64982 | 3187447 | 3 | 206866 |
| 92 | June, 15 2016 00:00:00 | 58684 | 3246131 | 3 | 265550 |
| 23 | June, 26 2016 00:00:00 | 46147 | 3292278 | 3 | 311697 |
| 46 | June, 30 2016 00:00:00 | 61921 | 3354199 | 3 | 373618 |
| 94 | July, 03 2016 00:00:00 | 55535 | 3409734 | 3 | 429153 |
| 60 | July, 07 2016 00:00:00 | 63607 | 3473341 | 3 | 492760 |
| 45 | July, 20 2016 00:00:00 | 51965 | 3525306 | 3 | 544725 |
| 96 | July, 20 2016 00:00:00 | 46684 | 3571990 | 3 | 591409 |
| 29 | August, 09 2016 00:00:00 | 37707 | 3609697 | 3 | 629116 |
| 69 | August, 11 2016 00:00:00 | 37194 | 3646891 | 3 | 666310 |
| 80 | August, 19 2016 00:00:00 | 62673 | 3709564 | 3 | 728983 |
| 36 | August, 28 2016 00:00:00 | 48237 | 3757801 | 3 | 777220 |
| 39 | August, 29 2016 00:00:00 | 48159 | 3805960 | 3 | 825379 |
| 25 | August, 30 2016 00:00:00 | 60958 | 3866918 | 3 | 886337 |
| 68 | September, 04 2016 00:00:00 | 50167 | 3917085 | 3 | 936504 |
| 55 | September, 08 2016 00:00:00 | 31193 | 3948278 | 3 | 967697 |
| 64 | September, 10 2016 00:00:00 | 31157 | 3979435 | 3 | 998854 |
| 42 | September, 14 2016 00:00:00 | 52878 | 4032313 | 4 | 52878 |
| 43 | September, 15 2016 00:00:00 | 54728 | 4087041 | 4 | 107606 |
| 77 | September, 18 2016 00:00:00 | 65320 | 4152361 | 4 | 172926 |
| 12 | September, 23 2016 00:00:00 | 43597 | 4195958 | 4 | 216523 |
| 30 | September, 26 2016 00:00:00 | 32764 | 4228722 | 4 | 249287 |
| 10 | September, 27 2016 00:00:00 | 47038 | 4275760 | 4 | 296325 |
| 47 | October, 08 2016 00:00:00 | 46280 | 4322040 | 4 | 342605 |
| 26 | October, 10 2016 00:00:00 | 69487 | 4391527 | 4 | 412092 |
| 63 | October, 30 2016 00:00:00 | 49561 | 4441088 | 4 | 461653 |
| 78 | November, 15 2016 00:00:00 | 40138 | 4481226 | 4 | 501791 |
| 27 | November, 27 2016 00:00:00 | 57378 | 4538604 | 4 | 559169 |
| 21 | December, 01 2016 00:00:00 | 35336 | 4573940 | 4 | 594505 |
| 16 | December, 03 2016 00:00:00 | 39671 | 4613611 | 4 | 634176 |
| 22 | December, 13 2016 00:00:00 | 34574 | 4648185 | 4 | 668750 |
| 72 | January, 29 2017 00:00:00 | 55084 | 4703269 | 4 | 723834 |
| 44 | January, 30 2017 00:00:00 | 36742 | 4740011 | 4 | 760576 |
| 24 | February, 01 2017 00:00:00 | 31061 | 4771072 | 4 | 791637 |
| 76 | February, 12 2017 00:00:00 | 35059 | 4806131 | 4 | 826696 |
| 9 | February, 27 2017 00:00:00 | 39767 | 4845898 | 4 | 866463 |
| 11 | February, 28 2017 00:00:00 | 66007 | 4911905 | 4 | 932470 |

I took a look again and couldnt solve it with a Windows Function so I took the recursive aproach
SQL Fiddle Demo
Sample Data: 100 rows random dates between 2015-2017 amounts between 10k - 70k
DROP TABLE IF EXISTS "myTable";
CREATE TABLE "myTable" (
id SERIAL PRIMARY KEY,
day_t varchar(255),
collect integer NULL
);
INSERT INTO "myTable" (day_t,collect) VALUES ('2015-04-10',65825),('2015-09-07',39408),('2015-07-26',58672),('2015-06-04',46891),('2016-02-05',53953),('2015-09-17',65957),('2016-04-27',33368),('2016-03-25',51809),('2017-02-27',39767),('2016-09-27',47038);
INSERT INTO "myTable" (day_t,collect) VALUES ('2017-02-28',66007),('2016-09-23',43597),('2015-03-25',69484),('2015-09-09',40234),('2015-05-19',50847),('2016-12-03',39671),('2016-05-17',35416),('2015-11-23',44925),('2015-10-14',48509),('2015-08-27',36882);
INSERT INTO "myTable" (day_t,collect) VALUES ('2016-12-01',35336),('2016-12-13',34574),('2016-06-26',46147),('2017-02-01',31061),('2016-08-30',60958),('2016-10-10',69487),('2016-11-27',57378),('2016-01-23',40250),('2016-08-09',37707),('2016-09-26',32764);
INSERT INTO "myTable" (day_t,collect) VALUES ('2015-07-10',39649),('2016-02-11',44988),('2015-11-09',41944),('2015-11-11',35516),('2015-09-30',49446),('2016-08-28',48237),('2015-06-28',54315),('2015-06-09',64732),('2016-08-29',48159),('2015-11-05',67293);
INSERT INTO "myTable" (day_t,collect) VALUES ('2015-03-30',56404),('2016-09-14',52878),('2016-09-15',54728),('2017-01-30',36742),('2016-07-20',51965),('2016-06-30',61921),('2016-10-08',46280),('2015-10-28',58527),('2015-03-27',57412),('2015-05-11',39641);
INSERT INTO "myTable" (day_t,collect) VALUES ('2015-05-17',32895),('2016-04-23',47772),('2016-02-25',68948),('2016-01-02',32330),('2016-09-08',31193),('2015-10-26',30072),('2015-07-14',60394),('2015-05-11',49759),('2015-06-30',34885),('2016-07-07',63607);
INSERT INTO "myTable" (day_t,collect) VALUES ('2016-05-17',64603),('2015-12-24',34678),('2016-10-30',49561),('2016-09-10',31157),('2016-01-25',49404),('2015-05-29',66332),('2015-12-25',35323),('2016-09-04',50167),('2016-08-11',37194),('2016-01-06',47875);
INSERT INTO "myTable" (day_t,collect) VALUES ('2015-07-08',46440),('2017-01-29',55084),('2016-01-26',65879),('2015-08-20',37972),('2015-10-12',31448),('2017-02-12',35059),('2016-09-18',65320),('2016-11-15',40138),('2015-06-14',62843),('2016-08-19',62673);
INSERT INTO "myTable" (day_t,collect) VALUES ('2015-12-28',37071),('2016-03-25',66506),('2016-03-11',47244),('2016-04-27',57644),('2015-11-20',43920),('2015-10-11',34291),('2016-06-07',41865),('2016-04-06',69288),('2016-04-14',43162),('2015-03-11',69880);
INSERT INTO "myTable" (day_t,collect) VALUES ('2015-07-12',65048),('2016-06-15',58684),('2015-09-29',47213),('2016-07-03',55535),('2015-08-19',52393),('2016-07-20',46684),('2016-06-08',64982),('2015-07-20',34481),('2015-04-03',59426),('2015-04-27',60884);
Create a row_number to perform the recursion need consecutive ID's
CREATE TABLE sortDates as
SELECT day_t,
collect,
row_number() over (order by day_t) rn
FROM "myTable";
Recursive Query
If you see the CASE if previous total m.collect is bigger than 1 million the total is reset.
WITH RECURSIVE million(rn, day_t, collect) AS (
(
SELECT rn, day_t, collect
FROM sortDates
WHERE rn = 1
)
UNION
(
SELECT s.rn, s.day_t, CASE WHEN m.collect > 1000000 THEN s.collect
ELSE m.collect + s.collect
END as collect
FROM sortDates s
JOIN million m
ON s.rn = m.rn + 1
)
)
SELECT *
FROM million
WHERE collect > 1000000
Finally just bring the rows where you break the 1 million limit.
OUTPUT
| rn | day_t | collect |
|----|------------|---------|
| 19 | 2015-07-10 | 1028544 |
| 41 | 2015-11-23 | 1024545 |
| 62 | 2016-05-17 | 1027511 |
| 82 | 2016-09-15 | 1006441 |

Symfony2 Query to find last working date from Holiday Calender

I had a calender entity in my project which manages the open and close time of business day of the whole year.
Below is the record of a specific month
id | today_date | year | month_of_year | day_of_month | is_business_day
-------+---------------------+------+---------------+-------------+---------------+
10103 | 2016-02-01 00:00:00 | 2016 | 2 | 1 | t
10104 | 2016-02-02 00:00:00 | 2016 | 2 | 2 | t
10105 | 2016-02-03 00:00:00 | 2016 | 2 | 3 | t
10106 | 2016-02-04 00:00:00 | 2016 | 2 | 4 | t
10107 | 2016-02-05 00:00:00 | 2016 | 2 | 5 | t
10108 | 2016-02-06 00:00:00 | 2016 | 2 | 6 | f
10109 | 2016-02-07 00:00:00 | 2016 | 2 | 7 | f
10110 | 2016-02-08 00:00:00 | 2016 | 2 | 8 | t
10111 | 2016-02-09 00:00:00 | 2016 | 2 | 9 | t
10112 | 2016-02-10 00:00:00 | 2016 | 2 | 10 | t
10113 | 2016-02-11 00:00:00 | 2016 | 2 | 11 | t
10114 | 2016-02-12 00:00:00 | 2016 | 2 | 12 | t
10115 | 2016-02-13 00:00:00 | 2016 | 2 | 13 | f
10116 | 2016-02-14 00:00:00 | 2016 | 2 | 14 | f
10117 | 2016-02-15 00:00:00 | 2016 | 2 | 15 | t
10118 | 2016-02-16 00:00:00 | 2016 | 2 | 16 | t
10119 | 2016-02-17 00:00:00 | 2016 | 2 | 17 | t
10120 | 2016-02-18 00:00:00 | 2016 | 2 | 18 | t
I want the get the today_date of last 7 working date. Supporse today_date is 2016-02-18 and date of last 7 working dates as 2016-02-09.

You can use row_number() for this like this:
SELECT * FROM
(SELECT t.*,row_number() OVER(order by today_date desc) as rnk
FROM Calender t
WHERE today_date <= current_date
AND is_business_day = 't')
WHERE rnk = 7
This will give you the row of the 7th business day from todays date

I see that you tagged your question with Doctrine, ORM and Datetime. Were you after a QueryBuilder solution? Maybe this is closer to what you want:
$qb->select('c.today_date')
->from(Calendar::class, 'c')
->where("c.today_date <= :today")
->andWhere("c.is_business_day = 't'")
->setMaxResults(7)
->orderBy("c.today_date", "DESC")
->setParameter('today', new \DateTime('now'), \Doctrine\DBAL\Types\Type::DATETIME));