students(student_id, name, year, GPA, programs_code) instructors(instructor_id, name, title, salary, programs_code) programs(code, name, division, instructor_id) course(course_name, credit, domain, course_number) enroll(student_id, instructor_id, course_name) 1. Create tables according to the schema. 2. Use check or assertion to make sure instructors salary > 5000. 3. Use trigger to deal with cascade delete.

1. Here is the SQL code to create the tables according to the schema:

CREATE TABLE students (
  student_id INT PRIMARY KEY,
  name VARCHAR(50),
  year INT,
  GPA FLOAT,
  programs_code VARCHAR(10)
);

CREATE TABLE instructors (
  instructor_id INT PRIMARY KEY,
  name VARCHAR(50),
  title VARCHAR(50),
  salary FLOAT,
  programs_code VARCHAR(10),
  CHECK (salary > 5000)
);

CREATE TABLE programs (
  code VARCHAR(10) PRIMARY KEY,
  name VARCHAR(50),
  division VARCHAR(50),
  instructor_id INT,
  FOREIGN KEY (instructor_id) REFERENCES instructors (instructor_id) ON DELETE CASCADE
);

CREATE TABLE course (
  course_name VARCHAR(50) PRIMARY KEY,
  credit INT,
  domain VARCHAR(50),
  course_number INT
);

CREATE TABLE enroll (
  student_id INT,
  instructor_id INT,
  course_name VARCHAR(50),
  FOREIGN KEY (student_id) REFERENCES students (student_id) ON DELETE CASCADE,
  FOREIGN KEY (instructor_id) REFERENCES instructors (instructor_id),
  FOREIGN KEY (course_name) REFERENCES course (course_name)
);

2. The `CHECK` constraint has been added to the `instructors` table to ensure that the `salary` column is always greater than 5000. This will prevent any inserts or updates that would violate this rule.

3. Here is the SQL code to create a trigger that will handle cascade deletes:

CREATE TRIGGER delete_programs AFTER DELETE ON instructors
FOR EACH ROW
BEGIN
  DELETE FROM programs WHERE programs.instructor_id = OLD.instructor_id;
END;

This trigger will be executed after a row is deleted from the `instructors` table. It will delete all rows from the `programs` table where the `instructor_id` matches the deleted row's `instructor_id`. This will ensure that there are no orphaned rows in the `programs` table when an instructor is deleted.