Defining Referential Constraints

[Lani2000]

The following is a brief overview of a coupple of queries I am using to create some tables with constraints. My questions should I switch step 4 and 5?
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Step 1, create the employee table:
Step 2, create the department table:

Step 3, add the constraint to the employee table:
alter table employee
add (constraint empdnoFRK foreign key (dno)
references department (dnumber));

Step 4, enable the constraints:
alter table employee enable constraint empsuperFRK;
alter table department enable constraint departFRK;

Step 5, populate the tables:

[patel_dil]

Why do you need step 4? Constraints are enabled by default.