SELECT VALUE FROM V$OPTION WHERE PARAMETER = 'Oracle Label Security';
SELECT STATUS FROM DBA_OLS_STATUS WHERE NAME = 'OLS_CONFIGURE_STATUS';

exec SA_SYSDBA.create_policy('sss');

BEGIN
 SA_SYSDBA.CREATE_POLICY (
  policy_name      => 'emp_ols_pol',
  column_name      => 'ols_col',
  default_options  => 'read_control, update_control');
END;

alter session set events '6502 trace name errorstack level 3'; 
exec SA_SYSDBA.create_policy('sss');
select value from v$diag_info where name='Default Trace File';
exit

2017-11-16 23:06:16.585 : [ default][ default]ut_read_reg:2:ocr registry key SOFTWARE\Oracle\olr cannot be opened. error 2
2017-11-16 23:06:16.585 : [ default][ default]ut_read_reg:2:ocr registry key SOFTWARE\Oracle\ocr cannot be opened. error 2
2017-11-16 23:06:16.585 : [ default][ default]ut_read_reg:2:ocr registry key SOFTWARE\Oracle\olr cannot be opened. error 2
2017-11-16 23:06:16.585 : [ default][ default]ut_read_reg:2:ocr registry key SOFTWARE\Oracle\ocr cannot be opened. error 2

set serverout on
declare
   VERSION VARCHAR2(100);
   COMPAT NUMBER;
   STMT VARCHAR2(100);
   COMPAT_LEVEL VARCHAR2(100);
   QQQ VARCHAR2(100);
begin
   STMT := 'BEGIN SYS.DBMS_UTILITY.DB_VERSION(:ver,:compat); END;';
   EXECUTE IMMEDIATE STMT USING OUT VERSION, OUT COMPAT_LEVEL;
   QQQ := SUBSTR(COMPAT_LEVEL, 1,INSTR(COMPAT_LEVEL, '.', 1, 2) - 1);
   dbms_output.put_line('SUBSTR(COMPAT_LEVEL, 1,INSTR(COMPAT_LEVEL, ".", 1, 2) - 1) ---> ' || QQQ);
   COMPAT := TO_NUMBER('12,1');
   dbms_output.put_line('COMPAT_LEVEL: '||COMPAT_LEVEL);
   dbms_output.put_line('VERSION: '||VERSION);
   dbms_output.put_line('COMPAT: '||COMPAT);
end;

SUBSTR(COMPAT_LEVEL, 1,INSTR(COMPAT_LEVEL, ".", 1, 2) - 1) ---> 12.2
COMPAT_LEVEL: 12.2.0
VERSION: 12.2.0.1.0
COMPAT: 12,1
PL/SQL procedure successfully completed.

Error report -
ORA-06502: PL/SQL: : ошибка преобразования символа в число ошибка числа или значения
ORA-06512: на  line 12
06502. 00000 -  "PL/SQL: numeric or value error%s"
*Cause:    An arithmetic, numeric, string, conversion, or constraint error
           occurred. For example, this error occurs if an attempt is made to
           assign the value NULL to a variable declared NOT NULL, or if an
           attempt is made to assign an integer larger than 99 to a variable
           declared NUMBER(2).
*Action:   Change the data, how it is manipulated, or how it is declared so
           that values do not violate constraints.

NAME                   TYPE    VALUE  
---------------------- ------- ------ 
compatible             string  12.2.0 
noncdb_compatible      boolean FALSE  
plsql_v2_compatibility boolean FALSE