Strange Invalid identifier error oracle SQL

Question

I have this portion of a Oracle SQL query (lots more above it that doesn't apply to the question) ...

 authorw as (
    select a.id, (sum(p.w)) "theWeightOfTheAuthor"
    from ac a, pc p, authorpublication ap
    where a.id = ap.aid and ap.pid = p.id
    group by a.id)

select authorCount.id "ID", auth.name "NAME", authorCount.c "TOTAL_NUMBER_OF_PUBS", 
    athw.theWeightOfTheAuthor "W_SCORE", 
    (authorCount.C / athw.theWeightOfTheAuthor) "MULT"
from ac authorCount, authorw athw, Author auth
where authorCount.id = athw.id and authorCount.id = auth.id
order by TOTAL_NUMBER_OF_PUBS desc;

where I am receiving an error:

ORA-00904: "ATHW"."THEWEIGHTOFTHEAUTHOR": invalid identifier
00904. 00000 -  "%s: invalid identifier"
*Cause:    
*Action:
Error at Line: 404 Column: 22

Line 404 being the fourth from last line:

(authorCount.C / athw.theWeightOfTheAuthor) "MULT"

NOTE: I can access athw.id just fine, and if I execute up to the authorw creation, the table is printed out correctly with the theWeightOfTheAuthor column as expected. What gives?

Answer 1

Either remove the quotes around "theWeightOfTheAuthor" when you define it, or add quotes when you use it. Quoting the name when defining it makes the name case-sensitive, and because Oracle changes all non-quoted identifiers to UPPER CASE, your reference to the field is actually looking for ATHW.THEWEIGHTOFTHEAUTHOR, which doesn't exist.

A basic rule of Oracle programming is - never quote identifiers. It's a pain. Just don't do it.

Best of luck.

Answer 2

You've specified the column alias in double quotes, with mixed case, as "theWeightOfTheAuthor" . When you use double quotes for a column name, Oracle preserves case. When you refer to it without quotes, as athw.theWeightOfTheAuthor , Oracle automatically converts it to upper-case. So the two don't match.

My suggestion is to remove the double quotes from the alias, so it will also be interpreted as upper-case. Alternatively, you could use double quotes for all references to this column, but I don't see any benefit to using mixed case in the column name. (You can still write it as mixed case, for readability, but Oracle will see it as all upper case.)