Membuat Tabel SQL

USE PBD;

CREATE TABLE MAHASISWA(
THANG INTEGER NOT NULL,
NIM INTEGER NOT NULL,
NAMA VARCHAR (30) NOT NULL,
ALAMAT VARCHAR (80) DEFAULT 'YOGYA',
TGL DATETIME);
ALTER TABLE MAHASISWA ADD CONSTRAINT PK_MHS PRIMARY KEY (NIM);

CREATE TABLE DOSEN (
NIP INTEGER NOT NULL PRIMARY KEY,
NAMA VARCHAR(30)NOT NULL);

CREATE TABLE MATAKULIAH (
KODE CHAR(2) NOT NULL PRIMARY KEY,
MATAKULIAH VARCHAR(30) NOT NULL,
SKS INTEGER DEFAULT 2);

CREATE TABLE KELAS (
IDKELAS INTEGER IDENTITY (0,1) PRIMARY KEY,
KODE CHAR (2) NOT NULL,
NIP INTEGER NOT NULL);

ALTER TABLE KELAS ADD CONSTRAINT FK_KELAS1 FOREIGN KEY (KODE)
REFERENCES MATAKULIAH (KODE)
ON UPDATE CASCADE
ON DELETE NO ACTION;

ALTER TABLE KELAS ADD CONSTRAINT FK_KELAS2 FOREIGN KEY (NIP)
REFERENCES DOSEN (NIP)
ON UPDATE CASCADE
ON DELETE NO ACTION;

CREATE TABLE KRS (
NIM INTEGER NOT NULL,
IDKELAS INTEGER NOT NULL,
NILAI INTEGER DEFAULT 0,
PRIMARY KEY (NIM, IDKELAS));

ALTER TABLE KRS ADD CONSTRAINT FK_KRS1 FOREIGN KEY (NIM)
REFERENCES MAHASISWA (NIM)
ON UPDATE CASCADE
ON DELETE NO ACTION;

ALTER TABLE KRS ADD CONSTRAINT FK_KRS2 FOREIGN KEY (IDKELAS)
REFERENCES KELAS (IDKELAS)
ON UPDATE CASCADE
ON DELETE NO ACTION;