Help with select into please

Question

Good morning everyone,
I have a problem with my function. I need to do the dynamic select with the SELECT INTO
create or replace function prueba (p_param IN VARCHAR2) RETURN VARCHAR2
IS
v_aux1 VARCHAR2(200);
v_aux2 VARCHAR2(200);
BEGIN
SELECT col1
INTO v_aux1
FROM my_table
WHERE col2 = p_param; --UNION SELECT '1233' FROM DUAL;
RETURN v_aux1;
EXCEPTION
WHEN OTHERS THEN
RAISE_APPLICATION_ERROR(-20000,SQLERRM );
--RETURN v_aux2;
END;
When I try to call my function with the golden as follows:
select (prueba('''MON'' UNION SELECT '||chr(039)||'12'||chr(039)||' FROM DUAL')) from dual
OR
select (prueba(chr(039)||'MON'||chr(039)||' UNION SELECT '||chr(039)||'12'||chr(039)||' FROM DUAL')) from dual
I get the error: no data found
If I use the sentence in Golden or SQLPLUS as follows:
SELECT col1
-- INTO aux1
FROM my_table
WHERE despaise = 'MON' UNION SELECT '12' FROM DUAL
It ´s correct, and it return '1233'
The value 'MON' no exists in my_table.
If uncommented the sentence "UNION SELECT '1233' FROM DUAL" in my function an I use 'MON' as parameter it´s correct.
How I can do this using the parameter with the UNION?.
Thank you very much to all and sorry for my english

Answer 1

Hi,
welcome to the forum.
Please read SQL and PL/SQL FAQ
When you put some code or output please enclose it between two lines starting with {noformat}{noformat}
i.e.:
{noformat}{noformat}
SELECT ...
{noformat}{noformat}
you cannot pass static SQL as part of the string.
When you call the procedure in either wayselect (prueba('''MON'' UNION SELECT '||chr(039)||'12'||chr(039)||' FROM DUAL')) from dual
select (prueba(chr(039)||'MON'||chr(039)||' UNION SELECT '||chr(039)||'12'||chr(039)||' FROM DUAL')) from dual
This result in passing a whole string to your function as'MON' UNION SELECT '12' FROM DUAL
which translates in your code asSELECT col1
INTO v_aux1
FROM my_table
WHERE col2 = '''MON'' UNION SELECT ''12'' FROM DUAL'
So it is searching a rows having col2 with value  '''MON'' UNION SELECT ''12'' FROM DUAL'
Please try to explain what you are trying to achieve and we may help you.
You could use dynamic SQL to do that but it is not clear what are your business requirement and the approach that you are using does not seem to be correct.
Regards.
Al