Calling a function which has a CLOB parameter via an anonymous block.

Question

OK,
we are moving a lot of exports currently done by Crystal to just be done by stored procs.
So we have a load of existing, some extremely length SQL statements used for these exports.
IN the exports, we have meaningful column headings, so we have a 'lookup' file where all the column names are listed with the desired column name text listed against it.
So - to make our lives easier(i thought) , I have written a Oracle function to extract al;l of the column names as a list (see below).
It works fine except for when I am trying to pass in a SQL treatment that is longer than 4000 character.
What I want to be able to do is simply have an anonymous block that callls my function, I will be running this via SQL explorer.
Something like......
DECLARE
theSQL CLOB;
BEGFIN
theSQL := 'SELECT * FROM ORDERS WHERE 1=0';
SELECT GET_COLUNS_AS_LIST( theSQL, 0 ) FROM DUAL;
END;
However, when I run this I get the error................
PLS-00428: an INTO clause is expected in this SELECT statement
06550. 00000 - "line %s, column %s:\n%s"
*Cause:    Usually a PL/SQL compilation error.
If I hard code the SQL like this, SELECT GET_COLUNS_AS_LIST( 'SELECT * FROM ORDERS WHERE 1=0', 0 ) FROM DUAL; all is well.
Also, I am going to need to be able to pass in SQL ststement longer that 4000 characters as weel so please bear that in mind.
I am not an Oracle guy, so I guess I am missing something fundamental - Please enlighten me with regards to this.
Any help extremely appreciated.
CREATE OR REPLACE FUNCTION GET_COLUNS_AS_LIST( P_SQL IN VARCHAR2, Add_Equals_Sign Number := 0)
RETURN CLOB
IS
fResult VARCHAR2(32000);
HNDL NUMBER;
d NUMBER;
colCount INTEGER;
i INTEGER;
rec_tab DBMS_SQL.DESC_TAB;
cCRLF VARCHAR(2) := CHR(13) || CHR(10);
LONG_SQL dbms_sql.varchar2s;
n INTEGER;
l INTEGER;
u INTEGER;
StartPos INTEGER;
BEGIN
--INITIIALISE RESULT
fResult := '';
HNDL := DBMS_SQL.OPEN_CURSOR;
l := Length( P_SQL );
u := ( l / 1000 ) + 1;
FOR n IN 1..u
LOOP
StartPos := ( n - 1 ) + 1;
LONG_SQL( n ) := SubStr( P_SQL, StartPos, 1000 );
END LOOP;
if HNDL <> 0 THEN
DBMS_SQL.PARSE ( c => HNDL,
statement => LONG_SQL,
lb => 1,
ub => u,
lfflg => false,
language_flag => DBMS_SQL.NATIVE );
--DBMS_SQL.PARSE( HNDL, P_SQL, DBMS_SQL.NATIVE);
d := DBMS_SQL.EXECUTE( HNDL );
DBMS_SQL.DESCRIBE_COLUMNS( HNDL, colCount, rec_tab);
FOR i in 1..colCount
LOOP
IF Add_Equals_Sign > 0 AND i > 1 THEN
fResult := ltrim( fResult || '=' || cCRLF || UPPER( rec_tab( i ).col_name ), cCRLF );
ELSE
fResult := ltrim( fResult || cCRLF || UPPER( rec_tab( i ).col_name ), cCRLF );
END IF;
END LOOP;
IF Add_Equals_Sign > 0 THEN
fResult := fResult ||'=';
END IF;
ELSE
fResult := '!!COULD NOT OPEN CURSOR!!';
fResult := P_SQL;
END IF;
RETURN fResult;
--Tidy Up 
DBMS_SQL.CLOSE_CURSOR(HNDL);
Return 'EGG';
END;
--EXAMPLE USAGE
--Select GET_COLUNS_AS_LIST
--Select * from SALES_TYPE
--', 1) FROM DUAL;

Answer 1

So I have ended up with this.
When I next get some time, I'd like to be able to strip out the table and simply output the results to an SQL Developer script window without having to go through the table.
Now this works - but if you see that I am doing something wrong - please point it out.
Many thanks,
Ant
CREATE OR REPLACE FUNCTION GET_COLUNS_AS_LIST( P_SQL IN CLOB, Add_Equals_Sign Number := 0)
RETURN VARCHAR2
IS
fResult VARCHAR2(32000);
HNDL NUMBER;
d NUMBER;
colCount INTEGER;
i INTEGER;
ChunkSize INTEGER;
rec_tab DBMS_SQL.DESC_TAB;
cCRLF VARCHAR(2) := CHR(13) || CHR(10);
LONG_SQL dbms_sql.varchar2s;
n INTEGER;
l INTEGER;
u INTEGER;
StartPos INTEGER;
BEGIN
--INITIIALISE RESULT
HNDL := 0;
ChunkSize := 4;
fResult := '';
--fResult := fResult|| 'A'; 
HNDL := DBMS_SQL.OPEN_CURSOR;
--l := Length( P_SQL );
l := dbms_lob.getLength( P_SQL );
--l := 50;
u := Round( l / ChunkSize ) + 1;
--fResult := fResult|| 'B';   
FOR n IN 1..u
LOOP
StartPos := ( ( n - 1 ) * ChunkSize ) + 1;
IF StartPos = 0 THEN
StartPos := 1;
END IF;
--LONG_SQL( n ) := SubStr( P_SQL, StartPos, ChunkSize );
LONG_SQL( n ) := DBMS_LOB.SUBSTR( P_SQL, ChunkSize, StartPos );
END LOOP;
--fResult := fResult|| 'C';  
if HNDL <> 0 THEN
DBMS_SQL.PARSE ( c => HNDL,
statement => LONG_SQL,
lb => 1,
ub => u,
lfflg => false,
language_flag => DBMS_SQL.NATIVE );
--DBMS_SQL.PARSE( HNDL, P_SQL, DBMS_SQL.NATIVE);
d := DBMS_SQL.EXECUTE( HNDL );
DBMS_SQL.DESCRIBE_COLUMNS( HNDL, colCount, rec_tab);
--fResult := fResult|| 'D';  
FOR i in 1..colCount
LOOP
IF Add_Equals_Sign > 0 AND i > 1 THEN
fResult := ltrim( fResult || '=' || cCRLF || UPPER( rec_tab( i ).col_name ), cCRLF );
ELSE
fResult := ltrim( fResult || cCRLF || UPPER( rec_tab( i ).col_name ), cCRLF );
END IF;
END LOOP;
IF Add_Equals_Sign > 0 THEN
fResult := fResult ||'=';
END IF;
ELSE
fResult := '!!COULD NOT OPEN CURSOR!!';
END IF;
RETURN fResult;
--Tidy Up 
IF HNDL <> 0 THEN
DBMS_SQL.CLOSE_CURSOR(HNDL);
END IF;
END;
-- !!!!HOW TO USE THIS FUNCTION!!!!
BEGIN
EXECUTE IMMEDIATE ('DROP TABLE RPT_COLNAME_LOOKUPS;');
COMMIT;
EXECUTE IMMEDIATE ('CREATE TABLE RPT_COLNAME_LOOKUPS( COLUMN_NAME CLOB );');
COMMIT;
EXCEPTION WHEN OTHERS THEN NULL;
END;
DECLARE
theSQL Clob;
myresult CLOB;
BEGIN
--CLEAR OUT PREVIOUS RWS
DELETE FROM RPT_COLNAME_LOOKUPS; COMMIT;
--ASSIGN THE SQL TO RUN IT FOR 
theSQL := '
SELECT
EVENT.EVENT_ID AS COCK_SUCKER,
EVENT.EVENT_CODE, BLAH, BLAH, VERY LONG SQL STATEMENT';
--CALL THE FUNCTION PASSING IN THE SQL AND IF I WANT THE = OR NOT
SELECT GET_COLUNS_AS_LIST( theSQL, 1 ) INTO myresult FROM DUAL;
--INSERT THE RESULTS INTO A TABLE SO WE CAN GRAB THEM
INSERT INTO RPT_COLNAME_LOOKUPS SELECT myresult FROM DUAL;
COMMIT;
END;
--THEN LOOK AT THE COLUMNS NAMES IN THIS TABLE
--SELECT * FROM RPT_COLNAME_LOOKUPS;
--#############################################################################