CREATE TABLE Employee ( empno NUMERIC(4) NOT NULL, ename VARCHAR(20) NOT NULL, sal DECIMAL(7,2) NOT NULL, comm DECIMAL(7,2), hiredate DATE NOT NULL, deptno NUMERIC(2) REFERENCES Department ( deptno) , manager NUMERIC(4) REFERENCES Employee ( empno) , PRIMARY KEY ( empno ) ); CREATE TABLE Department ( deptno NUMERIC(2) NOT NULL, dname VARCHAR(20) NOT NULL, location VARCHAR(20) NOT NULL, PRIMARY KEY ( deptno ) ); CREATE TABLE SalGrade ( grade NUMERIC(2) NOT NULL, losal DECIMAL(7,2) NOT NULL, hisal DECIMAL(7,2) NOT NULL, PRIMARY KEY ( grade ) );