Can Anyone Tell the Reason WHY??????????????

Question

Just try this one
1. create table xclob(id number, text clob);
2. insert into xclob values(1,'ACCD_DebPresDcycHighOk_C');
3. commit
4. create index xclob_context on xclob(text) indextype is CTXSYS.CONTEXT;
5. select * from xclob where text like '%ACCD_DebPresDcycHighOk_C%';
Ans is :
ID TEXT
1 ACCD_DebPresDcycHighOk_C
6. select * from xclob where contains(text,'%ACCD_DebPresDcycHighOk_C%')>0;
No Records Returned.
7. select * from xclob where contains(text,'%ACCD\__DebPresDcycHighOk\__C%')>0;
No Records Returned.
7. select * from xclob where contains(text,'%ACCD%')>0;
Ans is :
ID TEXT
1 ACCD_DebPresDcycHighOk_C
Unable to Find the Reason

Answer 1

starting with the op's original sql:
SQL> select * from xclob where contains(text,'%ACCD_DebPresDcycHighOk_C%')>0;
no rows selected
-- use \ with only 1 underscore
SQL> select * from xclob where contains(text,'%ACCD\_DebPresDcycHighOk\_C%')>0;
        ID TEXT
         1 ACCD_DebPresDcycHighOk_C
1 row selected.
-- use 1 underscore, no slash, but put {} around whole thing
SQL> select * from xclob where contains(text,'{%ACCD_DebPresDcycHighOk_C%}')>0;
        ID TEXT
         1 ACCD_DebPresDcycHighOk_C
1 row selected.
SQL> select * from v$version;
BANNER
Oracle Database 10g Enterprise Edition Release 10.1.0.2.0 - Prod
PL/SQL Release 10.1.0.2.0 - Production
CORE    10.1.0.2.0      Production
TNS for 32-bit Windows: Version 10.1.0.2.0 - Production
NLSRTL Version 10.1.0.2.0 - Production
5 rows selected.so, I'm going to say, yes it does work that way.