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Занятие 29. Отработка основных операторов. Часть 1

📁 Блок: SQL / MySQL / Повторение и закрепление ⏱️ Время изучения: ~90 мин 🎯 Сложность: Средняя
#order #by #limit #offset #select #distinct #group #having #join #union

⚡ Кратко: команды

  • ORDER BY column [ASC|DESC]
  • LIMIT n OFFSET m
  • SELECT DISTINCT ...
  • GROUP BY ... HAVING ...
  • INNER/LEFT JOIN ... ON ...
  • SELECT ... UNION [ALL] SELECT ...

🔖 Справочник операторов

ORDER BY

SELECT * FROM products
ORDER BY unit_price DESC;

LIMIT и OFFSET

SELECT * FROM products
ORDER BY unit_price DESC
LIMIT 10 OFFSET 20;

DISTINCT

SELECT DISTINCT city FROM customers;
SELECT COUNT(DISTINCT city) FROM customers;

Агрегация и GROUP BY

SELECT city, COUNT(*) AS cnt
FROM customers
GROUP BY city
HAVING COUNT(*) > 5;

JOIN

SELECT o.id, c.first_name
FROM orders AS o
JOIN customers AS c ON o.customer_id = c.id;

UNION ALL

SELECT company FROM customers
UNION ALL
SELECT company FROM suppliers;

🔗 Полный справочник

Более полный каталог SQL-операторов курса — в справочнике SQL.