CREATE TABLE Employees ( 
    Eid integer Primary Key check (Eid > 0),
    username varchar(8) Not Null unique,
    LastName varchar(80) NOT NULL,
    FirstName varchar(80),
    Address varchar(255),
    City varchar(25) DEFAULT 'Nanaimo',
    ReportTo integer,
    -- ReportTo integer References Employees,
    Salary number(7, 2),
    Commission_pct number(2, 2),
    -- CONSTRAINT pk_EID PRIMARY KEY (Eid),
    Foreign Key (ReportTo) References Employees,
    Constraint check_sal CHECK (Salary * Commission_pct <= 50)
);