Trying to join two tables via subquery - sql

Question

Current query below
select
x.OVERALL_ID,
extract(year from y.tsdate) as year,
extract(month from y.tsdate) as month,
round(sum(y.grossamount),2) as "labour cost",
sum(y.reg)+sum(y.ot) as "labour hours"
from
(
select OVERALL_ID,
BOAT_NAME
from TV_VESSEL_VISIT
group by OVERALL_ID,VESSEL_NAME
order by OVERALL_ID, VESSEL_NAME
) as x
inner join
(
select *
from TRANS
where ratedesc = 'Labour'
and opsdesc = 'Ops'
and ACTDESC = 'Nature of Job'
and terminal = 'UKN'
and reconciled = 'Y'
and TSDATE between '20-JAN-01' and '20-JAN-31'
) as y on x.BOAT_NAME = y.BOATNAME
group by OVERALL_ID, extract(year from tsdate), extract(month from tsdate)
order by OVERALL_ID, extract(year from tsdate), extract(month from tsdate);
Desired result is OVERALL_ID's labour cost/hours grouped into year and month
Currently getting the below error
ORA-00933: SQL command not properly ended
00933. 00000 - "SQL command not properly ended"
*Cause:
*Action:
Error at Line: 14 Column: 3
Trying to follow this link https://www.geeksengine.com/database/subquery/subquery-in-join-operation.php

Answer 1

Orable allows AS when declaring a column alias, but does not allow it for a table alias. The subquery alias is the same case as table alias. try ) x instead of ) as x, and the same thing for y. This is one of the syntax errors that causes ORA-00933.

Answer 2

If using subqueries DO NOT use ORDER BY inside those subqueries. There is no good purpose to the ordering, it just isn't required.
Try this:
SELECT
x.OVERALL_ID
, extract(year FROM y.tsdate) AS year
, extract(month FROM y.tsdate) AS month
, round(sum(y.grossamount), 2) AS "labour cost"
, sum(y.reg) + sum(y.ot) AS "labour hours"
FROM (
SELECT DISTINCT
OVERALL_ID
, BOAT_NAME
FROM TV_VESSEL_VISIT
) x
INNER JOIN (
SELECT *
FROM TRANS
WHERE ratedesc = 'Labour'
AND opsdesc = 'Ops'
AND ACTDESC = 'Nature of Job'
AND terminal = 'UKN'
AND reconciled = 'Y'
AND TSDATE >= to_date('2020-01-01','yyy-mm-dd') AND TSDATE < to_date('2020-02-01','yyyy-mm-dd')
) y ON x.BOAT_NAME = y.BOATNAME
GROUP BY
OVERALL_ID
, extract(year FROM tsdate)
, extract(month FROM tsdate)
ORDER BY
OVERALL_ID
, extract(year FROM tsdate)
, extract(month FROM tsdate)
;
Notes: I have removed the unwanted ORDER BY in the upper subquery, and changed this to use SELECT DISTINCT (it will produce the same result as the previous group by subquery). Also I have changed the syntax used for the date range. Please avoid using 2 digit year references, always use the full year. Additionally I always recommend avoiding the use of between for date ranges it is far more predictable to use the combination of >= with < as you see above. Plus I have used to_date() so it is clear what dates I am using for the date range - which will give you every row of data relevant to January 2020.
The previous between syntax could possibly miss a whole day's data