CREATE TABLE Employee 
( 
	tfn       INTEGER, 
	union_nr  INTEGER, 
	CONSTRAINT Employee_PK PRIMARY KEY (tfn)
);


CREATE TABLE Technician
 (
       tfn       int    NOT NULL, 
       name      char(30)    NOT NULL, 
       address   char(20)    NOT NULL,
       phone     char(20)   NOT NULL,
       salary    int    NOT NULL,
         CONSTRAINT TFN_PK PRIMARY KEY (tfn)
         CONSTRAINT TFN_FK FOREIGN KEY (tfn) REFERENCES Employee (tfn)
 );

CREATE TABLE Trafficcontroller
(
	tfn       INT NOT NULL,
	lastMedicalCheck DATE NOT NULL,
	CONSTRAINT Controller_FK FOREIGN KEY (tfn) REFERENCES Employee,
	CONSTRAINT Controller_PK PRIMARY KEY (tfn)
);


Can't create table '.\airport\trafficcontroller.frm' (errno: 150)