CREATE TABLE Studentki2  (
nr_studentki NUMBER(6) CONSTRAINT nr_studentki_pk PRIMARY KEY,
nazwisko  VARCHAR2(15) CONSTRAINT nazwisko_nn_k NOT NULL,
imie VARCHAR2(15) CONSTRAINT imie_nn_k NOT NULL,
data_ur DATE,
plec CHAR(1) CONSTRAINT plec_CH_k CHECK(plec='K'));

INSERT INTO Studentki2
SELECT * FROM Studenci WHERE plec='K';