I have the following table on my Oracle database:
CREATE TABLE test
(
flight NUMBER(4),
date DATE,
action VARCHAR2(50),
CONSTRAINT pk PRIMARY KEY (flight,date)
);
and the following registers:
BEGIN
INSERT INTO test VALUES ('1234', '2020-02-29 18:00', 'Departure');
INSERT INTO test VALUES ('1234', '2020-02-29 19:00', 'Arrival');
INSERT INTO test VALUES ('4321', '2020-02-20 22:00', 'Departure');
INSERT INTO test VALUES ('4321', '2020-02-21 04:30', 'Arrival');
END;
/
My problem is that I want to make a SELECT that returns me the flight number only when it has departed and arrived at the same day. For example, flight '1234' has departed on day 29 and arrived on day 29, but in the other hand, the flight '4321' has departed on day 20 and arrived on day 21. I only would like to select the flight '1234', because it is the only one who meets the requeriments.
I have been thinking about the following select, but it doesn't work because the subquery returns more than just one value:
SELECT flight
FROM test
WHERE action = 'Departure'
AND TO_CHAR(date, 'YYYY-MM-DD') = (SELECT TO_CHAR(date, 'YYYY-MM-DD')
FROM test
WHERE action = 'Arrival');
Thank you so much.
You just need distinct action within a day. So, use HAVING count distinctly of two individual actions GROUPed BY flight and day :
SELECT flight
FROM test
WHERE action in ('Departure','Arrival')
GROUP BY flight, trunc("date")
HAVING COUNT(distinct action)=2
where there should be distinct
clause, need is observed if the sample data set is extended
date
is a reserved keyword and cannot be used as a column name for Oracle database. So, I preferred "date"
timestamp
keyword and add portion :00
at the end to represent second
such as timestamp'2020-02-21 04:30:00'
during the insertionWe don't know, whether a flight number in your data model uniquely represents a flight or not. We also don't know whether there can be any actions apart from 'Departure' and 'Arrival'.
The following solutions look at a flight number in combination with the flight date and consider the two actions in question, so they work in any case:
INTERSECT
:select flight, trunc(date) from test where action = 'Departure'
intersect
select flight, trunc(date) from test where action = 'Arrival';
select flight, trunc(date)
from test
group by flight, trunc(date)
having count(case when action = 'Departure' then 1 end) = 1
and count(case when action = 'Arrival' then 1 end) = 1;
You need the same table two time in join
SELECT t1.flight
FROM test t1
INNER JOIN test t2 ON t1.action = 'Departure'
AND TO_CHAR(t1.date, 'YYYY-MM-DD') = TO_CHAR(t2.date, 'YYYY-MM-DD')
AND t2.action = 'Arrival'
AND t1.flight =t2.flight
Or using the subquery ..use a proper FROM clause again
SELECT flight
FROM test
WHERE action = 'Departure'
AND (TO_CHAR(date, 'YYYY-MM-DD'), flight) = (
SELECT TO_CHAR(date, 'YYYY-MM-DD'), flight
FROM test
WHERE action = 'Arrival');
With COUNT()
window function:
select distinct flight
from (
select t.*,
count(distinct action) over (partition by flight, to_char("date", 'YYYY-MM-DD')) counter
from test t
)
where counter = 2
See the demo .
Results:
> | FLIGHT |
> | -----: |
> | 1234 |
Yet another option is to use the join
with flight number and date as follows:
SELECT distinct d.flight
FROM test d JOIN test a
ON d.action = 'Departure'
AND trunc(d.date) = trunc(a.date)
AND a.action = 'Arrival'
AND a.flight = d.flight;
Cheers!!
A PIVOT statement could work too
SELECT *
FROM (SELECT flight, date, action
FROM test)
PIVOT
(
MAX(DATE)
FOR ACTION IN ('Departure' AS DEP, 'Arrival' AS AR)
)WHERE TRUNC(DEP) = TRUNC(AR)
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