declare
    column_exists exception;
    pragma exception_init (column_exists , -01430);
begin
    execute immediate 'ALTER TABLE CATEGORIA ADD (INTEGRADOTOTVS NUMBER(1,0))';
    exception when column_exists then null;
end;
/
declare
    column_exists exception;
    pragma exception_init (column_exists , -01430);
begin
    execute immediate 'ALTER TABLE CATEGORIA ADD (ERRO VARCHAR2(4000 BYTE))';
    exception when column_exists then null;
end;