Creating an XML document through SQL, but I get syntax error - sql

Question

I have a small query to make an XML document:
Select XMLELEMENT(NAME movie,
XMLFOREST(Movie.name as title, year as year, rating as rating, plot_outline as plot,
XMLELEMENT(NAME actor, 'actor',
XMLAGG(
XMLELEMENT(NAME role, Acts.role )
),
XMLAGG(
XMLELEMENT(NAME person, Person.name))
)))
as result from Movie, Acts, Person
where Movie.mid = Acts.mid
and Acts.pid = Person.pid
But I get this error:
ERROR: unnamed XML element value must be a column reference
LINE 3: XMLELEMENT(NAME actor, 'actor',
^
This was supposed to be my expected result in XML:
<movie>
<title>Godfather, The</title>
<year>1972</year>
<rating>9.0</rating>
<plot>A Mafia boss' son, previously uninvolved in the business, takes over when his father is critically wounded in a mob hit.</plot>
<actor>
<role>Don Vito Corleone</role>
<person>Robert De Niro</person>
</actor>
<actor>
<role>Someone else</role>
<person>Someone else</person>
</actor>
</movie>
How do I get rid of this error message?

Answer 1

1) You can omit "name" word in xmlelement. xmlelment(name "name"... ) = xmlelment("name"...).
2) unnamed XML element value must be a column reference - that error is raise by xmlforest function.
xmlforest( col1, col2 as "TEST") - works fine
xmlforest(col1,xmlelement("TEST")) - throws error should be xmlforest(col1,xmlelement("TEST") as "xxx" )
3) XMLELEMENT(NAME actor, 'actor' you don need this. If i understand your query. You try to concatenate two xmlagg into one xmlelement. To do this use xmlconcat(xmlagg(..),xmlagg(..))
4) Finall query.
select xmlelement(
movie
, xmlforest(Movie.name as title
, year as year
, rating as rating
, plot_outline as plot
, xmlconcat(xmlagg(xmlelement(role, Acts.role)), xmlagg(xmlelement(person, Person.name))) as "actor"))
as result
from Movie, Acts, Person
where Movie.mid = Acts.mid and Acts.pid = Person.pid
You also have to add proper group by clause to it. Because it raise another exception. ORA-00937: not a single-group group function