Connected to Oracle Database 10g Release 10.2.0.3.0 
Connected as system@ORCL

SQL> create user user1 identified by "1";

User created


SQL> grant resource to user1;

Grant succeeded


SQL> grant connect ot user1;
grant connect ot user1

ORA-00990: отсутствует или неверна привилегия

SQL> grant create session ot user1;
grant create session ot user1

ORA-00905: отсутствует ключевое слово

SQL> grant connect to user1;

Grant succeeded


SQL> conn user1/1
Connected to Oracle Database 10g Release 10.2.0.3.0 
Connected as user1

SQL> create table t(id number not null, dat1 date default sysdate not null, dat2 date default sysdate not null);

Table created


SQL> 
SQL> create trigger trg1 before insert or update on t for each row
  2  
  3  if :new.dat1 > date '2021-05-01' then
  4    raise_appplication_error(-20001, 'Error');
  5  end if;
  6  
  7  end;
  8  /
create trigger trg1 before insert or update on t for each row

if :new.dat1 > date '2021-05-01' then
  raise_appplication_error(-20001, 'Error');
end if;

end;

ORA-04079: неверное определение триггера

SQL> create or replace trigger trg1 before insert or update on t for each row
  2  
  3  begin
  4  
  5  if :new.dat1 > date '2021-05-01' then
  6    raise_appplication_error(-20001, 'Error');
  7  end if;
  8  
  9  end;
 10  /

Warning: Trigger created with compilation errors


SQL> show errors;
Errors for TRIGGER USER1.TRG1:
LINE/COL ERROR
-------- ------------------------------------------------------------------------
4/3      PLS-00201: идентификатор 'RAISE_APPPLICATION_ERROR' должен быть объявлен
4/3      PL/SQL: Statement ignored

SQL>