PL/SQL - use same pipelined function twice in the same query - sql

Question

I'm trying to use a pipelined function to save on time and reduce redundancy in my queries.
The function in question returns data from a reference table based on some input. Records in the main data table I am selecting from have multiple columns that all refer to the reference table. The problem I run into is that when I try to use the pipelined function more than once in the query, I get a "cursor already open" error.
For example:
select xmlelement("genInf", xmlelement("ID", vt.ID),
xmlelement("vID", vt.V_ID),
xmlelement("vNum", vt.V_NUM),
xmlelement("terrDataCode", TERR_CODE.column_value), --data is based on reference table
xmlelement("ABValCode", AB_VAL_CD.column_value), --data is based on reference table
...
from V_TAB vt, table(UTIL.fn_getOvrdValXML(vt.terr_cd_id)) TERR_CODE,
table(UTIL.fn_getOvrdValXML(vt.ab_val_id)) AB_VAL_CD
where vt.ID = in_vID;
This worked fine until I added the second reference to my pipeline function (fn_getOvrdValXML), and I now get the "cursor already open" error.
The pipelined function is very simple:
type t_XMLTab is table of XMLType; --this type is in the spec
....
function fn_getOvrdValXML(in_ID in ovrd.id%type) return t_XMLTab
pipelined is
begin
for r in C_OvrdVal(in_ID) loop
pipe row(r.XMLChunk);
end loop;
return;
end;
The cursor is similarly simple:
cursor C_OvrdVal(in_ID in ovrd.id%type) is
select xmlforest(ID as "valueID", S_VAL as "sValue", U_VAL as "uplValue",
O_VAL as "oValue", O_IND as "oIndicator", F_VAL as "finalValue",
O_RSN as "reason") AS XMLChunk
from ovrd_val xov;
where xov.id = in_ID;
Is there a way to work around this, or should I try to tackle this problem (the problem of having to reference ovrd_val and output an xmlforest in the same way many many many many times) differently?
I admit I'm new to pipelined functions so I'm not 100% sure this is an appropriate use, but it made sense at the time and I'm open to other ideas ;)

Answer 1

If you're using pipeline functions, then you're on 9i minimum which means you can use the WITH clause:
WITH ovrdValXML AS (
select xov.id,
xmlforest(ID as "valueID", S_VAL as "sValue", U_VAL as "uplValue",
O_VAL as "oValue", O_IND as "oIndicator", F_VAL as "finalValue",
O_RSN as "reason") AS XMLChunk
from ovrd_val xov)
SELECT xmlelement("genInf", xmlelement("ID", vt.ID),
xmlelement("vID", vt.V_ID),
xmlelement("vNum", vt.V_NUM),
xmlelement("terrDataCode", TERR_CODE.column_value), --data is based on reference table
xmlelement("ABValCode", AB_VAL_CD.column_value), --data is based on reference table
...
FROM V_TAB vt
JOIN ovrdValXML terr_code ON terr_code = vt.?
AND terr_code.id = vt.terr_cd_id
JOIN ovrdValXML ab_val_cd ON ab_val_cd = vt.?
AND ab_val_cd.id = vt.ab_val_cd
WHERE vt.id = IN_VID;
Untested, and it's not clear what you're joining too - hence the ? on the join criteria.

Answer 2

Have you tried actually closing your cursor inside that pipelined function before piping row?
OPEN C_OvrdVal(in_ID);
FETCH c_OrdVal INTO my_chunk_variable;
CLOSE C_OrdVal;
PIPE ROW my_chunk_variable;
RETURN;