Приклади запитів
SELECT sum(duration) FROM `participation` WHERE 1;
SELECT COUNT(*) FROM `conference` WHERE `conf_date`<='2025-04-30' AND `conf_date`>='2025-04-01'
SELECT CONCAT(title, ' (', topic, ') - ', conf_date,', ',place, ' (',country,').') FROM `conference` WHERE 1
Простий спосіб:
SELECT conference_id, count(conference_id) FROM `participation`group by conference_id;
SELECT scientist_id, count(scientist_id) FROM `participation`group by scientist_id;
Складний спосіб:
SELECT scientist.name, participation.scientist_id, count(participation.scientist_id) FROM `participation` INNER JOIN scientist ON scientist.id=participation.scientist_id group by participation.scientist_id;
SELECT conference.title, participation.conference_id, count(participation.conference_id) FROM `participation` INNER JOIN conference ON conference.id=participation.conference_id group by participation.conference_id;