### Database Schema:
CREATE TABLE event (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	sport_id	INTEGER	NULL	DEFAULT NULL,
	event_name	TEXT	NULL	DEFAULT NULL,
	foreign key (sport_id) references sport (id)
);

CREATE TABLE noc_region (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	noc	TEXT	NULL	DEFAULT NULL,
	region_name	TEXT	NULL	DEFAULT NULL
);

CREATE TABLE sport (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	sport_name	TEXT	NULL	DEFAULT NULL
);

CREATE TABLE games (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	games_year	INTEGER	NULL	DEFAULT NULL,
	games_name	TEXT	NULL	DEFAULT NULL,
	season	TEXT	NULL	DEFAULT NULL
);

CREATE TABLE games_competitor (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	games_id	INTEGER	NULL	DEFAULT NULL,
	person_id	INTEGER	NULL	DEFAULT NULL,
	age	INTEGER	NULL	DEFAULT NULL,
	foreign key (games_id) references games (id),
	foreign key (person_id) references person (id)
);

CREATE TABLE city (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	city_name	TEXT	NULL	DEFAULT NULL
);

CREATE TABLE competitor_event (
	event_id	INTEGER	NULL	DEFAULT NULL,
	competitor_id	INTEGER	NULL	DEFAULT NULL,
	medal_id	INTEGER	NULL	DEFAULT NULL,
	foreign key (medal_id) references medal (id),
	foreign key (event_id) references event (id),
	foreign key (competitor_id) references games_competitor (id)
);

CREATE TABLE medal (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	medal_name	TEXT	NULL	DEFAULT NULL
);

CREATE TABLE games_city (
	games_id	INTEGER	NULL	DEFAULT NULL,
	city_id	INTEGER	NULL	DEFAULT NULL,
	foreign key (games_id) references games (id),
	foreign key (city_id) references city (id)
);

CREATE TABLE person (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	full_name	TEXT	NULL	DEFAULT NULL,
	gender	TEXT	NULL	DEFAULT NULL,
	height	INTEGER	NULL	DEFAULT NULL,
	weight	INTEGER	NULL	DEFAULT NULL
);

CREATE TABLE person_region (
	person_id	INTEGER	NULL	DEFAULT NULL,
	region_id	INTEGER	NULL	DEFAULT NULL,
	foreign key (person_id) references person (id),
	foreign key (region_id) references noc_region (id)
);

### User's Query:
Among the competitors with age ranges 24 and below, calculate the difference between the number of competitors who weighed greater than 70 kg and competitors who weighted less than 70 kg.

### Extra Knowledge:
SUBTRACT(COUNT(weight > 70), COUNT(weight < 70)) where age < 24;
SELECT COUNT(CASE WHEN T1.weight > 70 THEN 1 ELSE NULL END) - COUNT(CASE WHEN T1.weight < 70 THEN 1 ELSE NULL END) FROM person AS T1 INNER JOIN games_competitor AS T2 ON T1.id = T2.person_id WHERE T2.age < 24