### Database Schema:
CREATE TABLE taughtBy (
	course_id	INTEGER	NULL	PRIMARY KEY,
	p_id	INTEGER	NULL	PRIMARY KEY,
	foreign key (course_id) references course (course_id),
	foreign key (p_id) references person (p_id)
);

CREATE TABLE course (
	course_id	INTEGER	NULL	PRIMARY KEY,
	courseLevel	TEXT	NULL
);

CREATE TABLE person (
	p_id	INTEGER	NULL	PRIMARY KEY,
	professor	INTEGER	NULL,
	student	INTEGER	NULL,
	hasPosition	TEXT	NULL,
	inPhase	TEXT	NULL,
	yearsInProgram	TEXT	NULL
);

CREATE TABLE advisedBy (
	p_id	INTEGER	NULL	PRIMARY KEY,
	p_id_dummy	INTEGER	NULL	PRIMARY KEY,
	foreign key (p_id) references person (p_id),
	foreign key (p_id_dummy) references person (p_id)
);

### User's Query:
What is the ratio of professors and students?

### Extra Knowledge:
professors refers to professor = 1; students refers to student = 1; ratio = divide(count(person.p_id) when professor = 1, count(person.p_id) when student = 1)
SELECT CAST(SUM(CASE  WHEN professor = 1 THEN 1 ELSE 0 END) AS REAL) * 100 / SUM(CASE  WHEN student = 1 THEN 1 ELSE 0 END) AS per FROM person