Substr with more than 4000 characters gets ORA-06502: PL/SQL: numeric or value error

Question

In the below script if I try to substr for 4000 character it works and displays all text in my particular ID with respective DB field ID and Language, if I increase it even 4001 db pops up the error - ora-06502: pl/sql: numeric or value error.

Create or replace function GET_AER_TEXT5(M_AER_ID IN NUMBER,
  F_ID IN VARCHAR2,PREF_LANGUAGE IN VARCHAR2)
IS
  AERTEXT VARCHAR2(32000);
  LANG_PARAM VARCHAR2(2000);
  AER_CLOB CLOB;
BEGIN
  FOR c1 IN (
    select TEXT from AER_TEXT
    where FIELD_ID=F_ID and AER_ID=M_AER_ID and LANGUAGE IN(PREF_LANGUAGE)
  )
  LOOP
    IF c1.text IS NOT NULL THEN
      AER_CLOB:=AER_CLOB || c1.text;
    END IF;
  END LOOP;
  AERTEXT:=substr(AER_CLOB,1,4000);
  RETURN(AERTEXT);
END;

Importance of increasing this to more than 4000 is to pull complete text data. If the DB column contains more than 4K character it doesn't work.

I'm calling it with:

select AER_ID,GET_AER_TEXT5(AER_ID,at,field_id,'001')
from AER a,AER_TEXT AT
where AT.field_ID=12345 and a.aer_id=at.aer_id;

Can you please advise how to get rid of this issue.

Answer 1

Prior to Oracle 12c Oracle only allows 4000 bytes in a varchar2 value in an SQL context. You are allowed 32k in PL/SQL, so your function is sort of OK as it stands, even with the substrng getting the first 4001 characters; but only if you call it from PL/SQL. When you try to call it from SQL:

select AER_ID,GET_AER_TEXT5(AER_ID,at,field_id,'001') ...

... you're trying to assign a 4001-character value to the implicit SQL column in the return statement, and that is causing the error you are seeing.

You can either change your SAP call to use a PL/SQL context and a bind variable to get the return value, though you'll still be limited to 32k; or change your function to keep value as a CLOB, which makes the function a bit pointless as you can just get the value from the table. I'm not familiar with SAP so I'm not quite sure how you'd end up coding either approach.