Something

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)
 );