Reference table from subquery in Oracle - sql

Question

I have simplified my tables but essentially I have a table of accounts that have a cycle_no and end date. This end date is always set to the first of the month but I need to get the real end date by looking in the calendar details table. The real end date is the next date for this cycle_no.
To create the simplified tables and enter a few rows of data:
CREATE TABLE DATA_OWNER.ACCOUNT
(
ACCNO NUMBER(4),
CYCLE_NO NUMBER(4),
ENDDATE DATE
);
CREATE TABLE DATA_OWNER.CALENDAR_DETAILS
(
CALENDAR_DT DATE,
BILL_CYCL_NO NUMBER(4)
);
INSERT INTO calendar_Details
VALUES
('18/DEC/2017',
17);
INSERT INTO calendar_Details
VALUES
('23/DEC/2017',
20);
INSERT INTO calendar_Details
VALUES
('18/JAN/2018',
17);
INSERT INTO calendar_Details
VALUES
('23/JAN/2018',
20);
INSERT INTO calendar_Details
VALUES
('20/FEB/2018',
17);
INSERT INTO calendar_Details
VALUES
('21/FEB/2018',
20);
INSERT INTO account
VALUES
(1, 17, '01/DEC/2107');
INSERT INTO account
VALUES
(2, 20, '01/DEC/2107');
If we run this query though we get "ACC". "ENDDATE": invalid identifier:
SELECT accno, cycle_no, enddate, actual_date
FROM account acc
JOIN
(
SELECT MIN(calendar_dt) actual_date
FROM calendar_details cal
WHERE calendar_dt > acc.enddate
)
ON acc.cycle_no = cal.bill_cycl_no;
Can anyone give us some pointers on the best way to achieve this please?

Answer 1

You cannot refer to outer table references in a subquery in the FROM. Just use a correlated subquery:
SELECT accno, cycle_no, enddate,
(SELECT MIN(cal.calendar_dt) as actual_date
FROM calendar_details cal
WHERE cal.calendar_dt > acc.enddate AND acc.cycle_no = cal.bill_cycl_no
) as actual_date
FROM account acc;