* Only provide SQL code*

1. Use Oracle SQL to create a script file that declares table schema based on the following assumptions, and then inserts data records into the tables.

(a) Different departments have different names.

(b) A department may temporarily have no manager.

(c) Different employees may have the same name.

(d) An employee can work as a manager for at most one department.

(e) People who work in the HR department should earn at least 20,000 dollars.

(f) When deleting a record of an employee who is a manager, the managerID field of the department she/he works for should be set to null.

(g) When deleting a record of a department, the deptName field of all employees who work in that department should be set to null. All constraints must be declared before any actual data is inserted into tables.