how to correctly write an alias in a query SQL oracle

Question

This is my query

CREATE VIEW CourseQueuePositions AS
SELECT t2.code , t2.cid , 
(SELECT COUNT(*) as queue 
FROM Waits t1
WHERE t2.code = t1.code AND t1.queue# <= t2.queue#)
FROM Waits t2;

I keep getting this compile error Error at Command Line : 3 Column : 9 00998. 00000 - "must name this expression with a column alias"

although the Oracle SQL developer doesn't indicate any error beforehand. Also I believe that I am using the alias "query" so I really don't understand. Help would be appreciated

Answer 1

Try putting the alias after the subquery instead of after the column name within the subquery.

Although, I'd rewrite the query thus:

CREATE VIEW CourseQueuePositions AS
SELECT t2.code , t2.cid , count(t1.code) queue
FROM Waits t1, Waits t2
WHERE t2.code = t1.code AND t1.queue# <= t2.queue# ;

I don't have access to Oracle now so I can't test this out. But give it a shot.

Upon reviewing your query, it's hard to tell exactly you're trying to do. Can you update the question with example data and an explanation of what you're trying to do?

Answer 2

I have come up with the solution. Previously I added the alias in the inner subqueries SELECT statement, however that wasn't the correct way. What I should have done is to make an alias of the ENTIRE subquery. So something like this...

CREATE VIEW CourseQueuePositions AS 
SELECT t2.code, t2.cid, 
(SELECT COUNT(*) 
FROM Waits t1 
WHERE t1.code = t2.code AND t1.queue# <= t2.queue#) AS queue
FROM Waits t2;