CREATE TABLE EMPLOYEE (
SSN NUMBER NOT NULL,
LNAME VARCHAR(20),
BDATE DATE,
SALARY NUMBER,
JOBTYPE CHAR,
CONSTRAINT EMP_PK PRIMARY KEY (SSN)
);

CREATE TABLE SECRETARY (
SSN NUMBER NOT NULL,
TYPINGSPEED NUMBER,
CONSTRAINT SEC_PK PRIMARY KEY (SSN)
);

CREATE TABLE TECHNICIAN (
SSN NUMBER NOT NULL,
TGRADE CHAR(2),
CONSTRAINT TEC_PK PRIMARY KEY (SSN)
);

CREATE TABLE ENGINEER (
SSN NUMBER NOT NULL,
ENGTYPE VARCHAR(12),
CONSTRAINT ENG_PK PRIMARY KEY (SSN)
);