Sanalar bilan ishlash

Sanalar deyarli har bir bazada bor: tug‘ilgan kun, buyurtma vaqti, imtihon sanasi. Ular bilan ishlash bazalarda biroz farq qiladi — bu darsda ikkalasini ham ko‘rsatamiz.

Turlar

• date — faqat sana: 2026-11-14;
• timestamp (PostgreSQL) / datetime (MySQL) — sana va vaqt: 2026-11-14 18:30:00.

Sanalarni oddiy solishtirish mumkin — ular xuddi sonlardek tartiblanadi:

SELECT id, ordered_at FROM orders WHERE ordered_at >= '2026-10-25' ORDER BY ordered_at;

Bugungi sana

CURRENT_DATE — bugun, CURRENT_TIMESTAMP (yoki NOW()) — hozirgi vaqt. Ikkala bazada ham ishlaydi.

SELECT CURRENT_DATE AS today;

Sanadan qism ajratish: EXTRACT

SELECT id, ordered_at, EXTRACT(YEAR FROM ordered_at) AS y, EXTRACT(MONTH FROM ordered_at) AS m
FROM orders LIMIT 5;

EXTRACT ikkala bazada ham bor. Bundan tashqari:

PostgreSQL’da date_trunc — sanani oy, hafta yoki kungacha «kesadi»:

SELECT date_trunc('month', ordered_at) AS month, count(*) FROM orders GROUP BY 1 ORDER BY 1 DESC LIMIT 4;

Sanani chiroyli ko‘rinishda: to_char(ordered_at, 'DD.MM.YYYY').

Sanaga vaqt qo‘shish va farqni hisoblash

PostgreSQL’da interval:

SELECT id, ordered_at, ordered_at + interval '7 days' AS deadline FROM orders LIMIT 3;

Ikki sana farqi — delivered_at - ordered_at (natija interval), kunlarda: delivered_at::date - ordered_at::date.

Butun oy yoki yil bo‘yicha tanlash

BETWEEN '2026-10-01' AND '2026-10-31' vaqtli ustunda 31-oktabr soat 00:00 dan keyingi buyurtmalarni tashlab ketadi! Ishonchli usul — «keyingi oyning boshidan kichik»:

SELECT count(*) FROM orders WHERE ordered_at >= '2026-10-01' AND ordered_at < '2026-11-01';

Esda qoldiring

• Sanalar 'yil-oy-kun' ko‘rinishida yoziladi va oddiy solishtiriladi.
• EXTRACT(YEAR FROM sana) — ikkala bazada ishlaydi.
• Davr bo‘yicha tanlashda: >= boshlanish AND < keyingi davr boshi.