Question

I am new to using SQL developer.

This is hw for my class, and I’ve created employee – manager relationship table.

and for case a. if a manager loses his job, then the manager field should be set to null.

and for case b. if a manager loses his job, then his employee also loses his job.

my table looks like this

lastName | jobTitle | Department | employeeID | fk_employeeID | fk_employeeID1

I am not sure why I get 2 employeeIDs.

here is my DDL code:

CREATE TABLE Employee
(
    lastName varchar (255),
    jobTitle varchar (255),
    Department varchar (255),
    id_Employee integer,
    fk_Employeeid_Employee integer NOT NULL,
    fk_Employeeid_Employee1 integer,
    PRIMARY KEY(id_Employee),
    UNIQUE(fk_Employeeid_Employee),
    FOREIGN KEY(fk_Employeeid_Employee) REFERENCES Employee (id_Employee),
    FOREIGN KEY(fk_Employeeid_Employee1) REFERENCES Employee (id_Employee)
)

I think I have to use “on delete cascade” for a and b, if you know how to do it, please help.

Answer 1

Probably a little late for your homework, but in case someone else comes along.

CREATE TABLE Employee
(
    lastName varchar (255),
    jobTitle varchar (255),
    Department varchar (255),
    id_Employee integer,
    fk_Employeeid_Employee integer NOT NULL,
    fk_Employeeid_Employee1 integer,
    PRIMARY KEY(id_Employee),
    UNIQUE(fk_Employeeid_Employee),
    FOREIGN KEY(fk_Employeeid_Employee) REFERENCES Employee (id_Employee)
    ON UDPATE CASCADE ON DELETE SET NULL,
    FOREIGN KEY(fk_Employeeid_Employee1) REFERENCES Employee (id_Employee)
    ON UDPATE CASCADE ON DELETE SET NULL
)

I am not sure why you have multiple fk_employeeIDs… I am assuming this is the id of the employee’s manager. If this is the case, the code above should do what you want. If the manager is deleted, the fk_employeeID fields will be set to null. Also any changes to the manager’s id will be reflected in the foreign key field.

Hope that helps,