الوحدة 1 · الدرس 4 من 44/57 في الدورة~8 min

دروس الوحدة (4/4)

الفرز باستخدام ORDER BY

SQL does not guarantee the order of the rows returned by a SELECT: if you want a deterministic order, you have to ask for it explicitly with ORDER BY:

SQL

SELECT <colonne>
FROM   <tabella>
[WHERE <condizione>]
ORDER BY <colonna> [ASC|DESC] [, <altra-colonna> [ASC|DESC] …];

ASC is the default: ascending order (1 → 9, A → Z, old → recent).
DESC sorts descending (9 → 1, Z → A, recent → old).
You can sort by multiple columns: the second criterion breaks ties of the first.

Examples

SQL

-- Dal più recente assunto al più vecchio:
SELECT first_name, last_name, hired_on
FROM employees
ORDER BY hired_on DESC;

-- Per dipartimento crescente, poi per stipendio decrescente:
SELECT *
FROM employees
ORDER BY department_id, salary DESC;

Try it

تمرين#sql.m1.l4.e1

المحاولات: 0جارٍ التحميل…

Extract last name (last_name) and salary (salary) of all employees, sorted from the highest salary to the lowest.

جارٍ تحميل المحرر…

إظهار التلميح

ORDER BY salary DESC puts the highest-paid employees first.

الحل متاح بعد 3 من المحاولات

Review exercise

تمرين#sql.m1.l4.e2