Oracle searching a case insensive CLOB - oracle

Question

I have some code that searches a CLOB, which works fine. I'm attempting to wrap it in a function that I found online so the search can be CASE insensitive but I am running into some syntax errors and was hoping someone could help me out.
Below is my test CASE. I'm using livesql in can anyone wants to emulate my environment. Thanks in advance to all who answer.
create or replace type se_obj is object (s number, e number);
/
create or replace type se_tbl is table of se_obj;
/
create or replace function search_clob(p_lob clob, p_what varchar2)
return se_tbl
pipelined
as
len int := length(p_what);
s int;
pos int := 1;
begin
if p_lob is not null then
loop
s := instr(p_lob, p_what, pos);
exit when s = 0;
pipe row (se_obj(s, s + len - 1));
pos := s + len;
end loop;
end if;
return;
end;
/
CREATE OR REPLACE FUNCTION upper_clob(p_clob CLOB) RETURN CLOB
AS
v_clob CLOB; -- TEMPORARY CLOB TO WRITE TO
v_posn NUMBER := 1; -- CURRENT POSITION WITHIN CLOB
v_holder VARCHAR2(4000); -- CHARACTER STRING HOLDER
BEGIN
dbms_lob.createtemporary(v_clob,TRUE,dbms_lob.CALL);
WHILE (v_posn < dbms_lob.getlength(p_clob)) LOOP
v_holder := dbms_lob.substr(p_clob,4000,v_posn);
v_posn := v_posn + 4000;
v_holder := upper(v_holder);
dbms_lob.write(v_clob, length(v_holder),v_posn,v_holder);
END LOOP;
return v_clob;
end;
/
create table t ( x int primary key, y clob );
-- works fine
select t.x id, l.s start_pos, l.e end_pos, dbms_lob.getlength(y) clob_len
from t outer apply search_clob(y, 'hello world') l where l.s > 0
-- getting a syntax error
select t.x id, l.s start_pos, l.e end_pos, dbms_lob.getlength(y) clob_len
from t outer apply search_clob(upper_lob
(y), 'HELLO WORLD') l where l.s > 0

Answer 1

It's really overkill to call pl/sql functions for such purposes when you can easily achieve it in SQL...
Simple SQL example:
https://dbfiddle.uk/?rdbms=oracle_18&fiddle=13fa9071bd6ad34ebbf5fd6de4907a34
Test data:
create table t ( x int primary key, y clob );
insert into t
select
level,
to_clob('x')
||rpad(' ',4000,' ')||to_char(level,'0000')
||rpad(' ',4000,' ')||to_char(level,'0000')
||rpad(' ',4000,' ')||to_char(level,'0000')
as y
from dual
connect by level<=30;
commit;
Simple query:
select
x,
length(y) clob_len,
s.*
from t
outer apply(
select
nullif(instr(lower(t.y), :subs, 1, level),0) start_pos
,nullif(instr(lower(t.y), :subs, 1, level),0) + length('1') as end_pos
from dual
connect by instr(lower(t.y), :subs, 1, level)>0
) s
Or using modern SQL Macro: (tested on Oracle 19.11)
CREATE OR REPLACE FUNCTION search_clob(input_clob clob, search_string varchar2) return varchar2 SQL_MACRO is
BEGIN
RETURN q'{
select
nullif(instr(lower(search_clob.input_clob), search_clob.search_string, 1, level),0) start_pos
,nullif(instr(lower(search_clob.input_clob), search_clob.search_string, 1, level),0)
+ length(search_clob.search_string) as end_pos
from dual
connect by instr(lower(search_clob.input_clob), search_clob.search_string, 1, level)>0
}';
END;
/
select
x,
length(y) clob_len,
s.*
from t
outer apply search_clob(t.y, '1') s
Example using the first query:
SQL> var subs varchar2(10);
SQL> exec :subs:='1';
PL/SQL procedure successfully completed.
SQL> select
2 x,
3 length(y) clob_len,
4 s.*
5 from t
6 outer apply(
7 select
8 nullif(instr(lower(t.y), :subs, 1, level),0) start_pos
9 ,nullif(instr(lower(t.y), :subs, 1, level),0) + length('1') as end_pos
10 from dual
11 connect by instr(lower(t.y), :subs, 1, level)>0
12 ) s;
X CLOB_LEN START_POS END_POS
---------- ---------- ---------- ----------
1 12016 4006 4007
1 12016 8011 8012
1 12016 12016 12017
2 12016
3 12016
4 12016
5 12016
6 12016
7 12016
8 12016
9 12016
10 12016 4005 4006
10 12016 8010 8011
10 12016 12015 12016
11 12016 4005 4006
11 12016 4006 4007
11 12016 8010 8011
11 12016 8011 8012
11 12016 12015 12016
11 12016 12016 12017
12 12016 4005 4006
12 12016 8010 8011
12 12016 12015 12016
13 12016 4005 4006
13 12016 8010 8011
13 12016 12015 12016
14 12016 4005 4006
14 12016 8010 8011
14 12016 12015 12016
15 12016 4005 4006
15 12016 8010 8011
15 12016 12015 12016
16 12016 4005 4006
16 12016 8010 8011
16 12016 12015 12016
17 12016 4005 4006
17 12016 8010 8011
17 12016 12015 12016
18 12016 4005 4006
18 12016 8010 8011
18 12016 12015 12016
19 12016 4005 4006
19 12016 8010 8011
19 12016 12015 12016
20 12016
21 12016 4006 4007
21 12016 8011 8012
21 12016 12016 12017
22 12016
23 12016
24 12016
25 12016
26 12016
27 12016
28 12016
29 12016
30 12016
57 rows selected.