Optimising a SELECT query that runs slow on Oracle which runs quickly on SQL Server

SELECT orderID FROM tasks WHERE orderID NOT IN
(SELECT DISTINCT orderID FROM tasks WHERE
 engineer1 IS NOT NULL AND engineer2 IS NOT NULL)

SELECT DISTINCT orderID FROM tasks WHERE
engineer1 IS NOT NULL AND engineer2 IS NOT NULL

ANALYZE TABLE tasks COMPUTE STATISTICS;

ANALYZE TABLE tasks COMPUTE STATISTICS;

SELECT orderID FROM tasks WHERE orderID NOT EXISTS
    (SELECT DISTINCT orderID FROM tasks WHERE
         engineer1 IS NOT NULL AND engineer2 IS NOT NULL)`print("code sample");`

SELECT orderID AS oid FROM tasks WHERE NOT EXISTS
    (SELECT DISTINCT orderID AS oid2 FROM tasks WHERE
         engineer1 IS NOT NULL AND engineer2 IS NOT NULL and oid=oid2)

select orderid from tasks
minus
select orderid from tasks
where engineer1 IS NOT NULL AND engineer2 IS NOT NULL

select orderid from ORDERS
minus
select orderid from tasks
where engineer1 IS NOT NULL AND engineer2 IS NOT NULL

select orderid from ORDERS
where orderid not in
( select orderid from tasks
  where engineer1 IS NOT NULL AND engineer2 IS NOT NULL
)

select orderid from ORDERS
where not exists
( select null from tasks
  where tasks.orderid = orders.orderid
  and   engineer1 IS NOT NULL OR engineer2 IS NOT NULL
)

SELECT
    t.orderID
FROM
    tasks  t
    LEFT JOIN tasks t1
    	ON t.orderID =	t1.orderID
    	AND t1.engineer1 IS NOT NULL
    	AND t1.engineer2 IS NOT NULL
WHERE
    t1.orderID IS NULL

SELECT orderID FROM orders WHERE orderID NOT IN
(SELECT DISTINCT orderID FROM tasks WHERE
 engineer1 IS NOT NULL AND engineer2 IS NOT NULL)

SELECT
    o.orderID
FROM
    orders o
    LEFT JOIN tasks t
    	ON o.orderID =	t.orderID
    	AND t.engineer1 IS NOT NULL
    	AND t.engineer2 IS NOT NULL
WHERE
    t.orderID IS NULL

SELECT t1.orderID
FROM   tasks t1
WHERE  NOT EXISTS
       (SELECT 1
        FROM   tasks t2
        WHERE  t2.orderID   = t1.orderID
        AND    t2.engineer1 IS NOT NULL
        AND    t2.engineer2 IS NOT NULL)

SELECT orderID FROM tasks
WHERE engineer1 IS NOT NULL OR engineer2 IS NOT NULL

SELECT DISTINCT orderID FROM tasks t1 WHERE NOT EXISTS (SELECT * FROM tasks t2 WHERE t2.orderID=t1.orderID AND (engineer1 IS NOT NULL OR engineer2 IS NOT NULL));

SELECT orderID FROM tasks
MINUS
SELECT DISTINCT orderID FROM tasks WHERE engineer1 IS NOT NULL
AND engineer2 IS NOT NULL

SELECT orderID FROM tasks
MINUS
SELECT DISTINCT orderID FROM tasks WHERE
 engineer1 IS NOT NULL AND engineer2 IS NOT NULL

select distinct orderid
from
(
select orderid,
       max(case when engineer1 is null and engineer2 is null then 0 else 1)
          over (partition by orderid)
          as max_null_finder
from   tasks
)
where max_null_finder = 0

SELECT orderID
FROM tasks
GROUP BY orderID
HAVING COUNT(engineer1) = 0 AND COUNT(engineer2) = 0

SELECT DISTINCT orderID FROM Tasks
WHERE Engineer1 IS NULL OR Engineer2 IS NULL;

SELECT orderID
FROM tasks
WHERE orderID NOT IN (
  SELECT DISTINCT orderID
  FROM tasks
  WHERE engineer1 IS NOT NULL AND engineer2 IS NOT NULL
)
;

SELECT DISTINCT orderID
FROM tasks
WHERE NOT ( engineer1 IS NOT NULL AND engineer2 IS NOT NULL )
;

SELECT DISTINCT orderID
FROM tasks
WHERE engineer1 IS NULL OR engineer2 IS NULL
;

SELECT DISTINCT orderID
FROM tasks
WHERE (engineer1 IS NULL OR engineer2 IS NULL)

SELECT orderID
 FROM tasks
 GROUP BY orderID
 HAVING COUNT(engineer1) = 0 OR COUNT(engineer2) = 0