SQL> select * from dual where sysdate>=to_date(cast(sysdate-2 as char(10)));
select * from dual where sysdate>=to_date(cast(sysdate-2 as char(10)))
                                                      *
ERROR at line 1:
ORA-25137: Data value out of range

SQL>

create table tst_table(xz number, xz_date date);

create or replace procedure govnocode
as
  l_num  number;
  i      number := 0;
begin  
  while i < 11 loop
  
    select mod(trunc(dbms_random.value*10), 2)
    into l_num
    from dual;
    
    if l_num > 0 then
      insert into tst_table(xz    , xz_date)
      values               (l_num , sysdate);
    else 
      insert into tst_table(xz    , xz_date)
      values               (l_num , sysdate);
    end if;
    
   i := i + 1;
  
  end loop;
  
  commit;
  
end;
/

exec govnocode;
select * from tst_table;

drop table tst_table purge;
drop procedure govnocode;

SQL> select table_name from all_tables where table_name='Test';

TABLE_NAME
------------------------------
Test

SQL>

SQL> create table Test(id int,n varchar2(20));

Table created.

SQL> select * from Test;

no rows selected

SQL> select * from "Test";
select * from "Test"
              *
ERROR at line 1:
ORA-00942: table or view does not exist

SQL> create table "Test"(id int,"n" varchar2(20));

Table created.

SQL> select * from "Test";

no rows selected

SQL> select id,n from "Test";
select id,n from "Test"
          *
ERROR at line 1:
ORA-00904: "N": invalid identifier


SQL> select id,"n" from "Test";

no rows selected

SQL> desc test
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 ID                                                 NUMBER(38)
 N                                                  VARCHAR2(20)

SQL> desc "Test";
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 ID                                                 NUMBER(38)
 n                                                  VARCHAR2(20)


SQL> insert into Test values(1,'Stax');

1 row created.

SQL> insert into "Test" values(1,'Stanislav');

1 row created.

SQL> select * from Test;

        ID N
---------- --------------------
         1 Stax

SQL> select * from "Test";

        ID n
---------- --------------------
         1 Stanislav

SQL>
SQL>

SQL> create table їжачок(голка int);

Table created.

SQL> desc їжачок;
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 ГОЛКА                                              NUMBER(38)

SQL> select * from all_tables where table_name='їжачок';

no rows selected

SQL> select table_name from all_tables where table_name=upper('їжачок');

TABLE_NAME
------------------------------
ЇЖАЧОК

SQL> select * from їжачок;

no rows selected

SQL> select * from "їжачок";
select * from "їжачок"
              *
ERROR at line 1:
ORA-00942: table or view does not exist