SQL TOP / LIMIT / ROWNUM

SQL SELECT TOP bandi

Qaytariladigan yozuvlar sonini LIMIT uchun SELECT TOP bandi ishlatiladi.

SELECT TOP bandi minglab yozuvlarga ega katta jadvallarda juda foydalidir. Katta hajmdagi ma’lumotlarni bir vaqtda qaytarish tizim unumdorligiga ta’sir qilishi mumkin.

Quyidagi SQL "Customers" jadvalining faqat dastlabki 3 ta yozuvini tanlaydi:

Misol

SELECT Customers jadvalining faqat dastlabki 3 ta yozuvi:

SELECT TOP 3 * FROM Customers;

O‘zingiz sinab ko‘ring »

Eslatma: Barcha ma’lumotlar bazasi tizimlari ham SELECT TOP bandini qo‘llab-quvvatlamaydi. MySQL cheklangan miqdordagi yozuvlarni tanlash uchun LIMIT bandini qo‘llab-quvvatlaydi, Oracle esa FETCH FIRST n ROWS ONLY dan foydalanadi.

SQL Server / MS Access uchun sintaksis

SELECT TOP number|percent column_name(s) FROM table_nameWHERE condition;

MySQL uchun sintaksis

SELECT column_name(s) FROM table_name WHERE condition LIMIT number;

Oracle 12+ uchun sintaksis

SELECT column_name(s) FROM table_name ORDER BY column_name(s) FETCH FIRST number ROWS ONLY;

Demo ma’lumotlar bazasi

Quyida misollarda foydalanilgan Customers jadvalidan tanlanma keltirilgan:

CustomerID	CustomerName	ContactName	Address	City	PostalCode	Country
1	Alfreds Futterkiste	Maria Anders	Obere Str. 57	Berlin	12209	Germany
2	Ana Trujillo Emparedados y helados	Ana Trujillo	Avda. de la Constitución 2222	México D.F.	05021	Mexico
3	Antonio Moreno Taquería	Antonio Moreno	Mataderos 2312	México D.F.	05023	Mexico
4	Around the Horn	Thomas Hardy	120 Hanover Sq.	London	WA1 1DP	UK
5	Berglunds snabbköp	Christina Berglund	Berguvsvägen 8	Luleå	S-958 22	Sweden

MySQL - LIMIT bandi

Quyidagi SQL MySQL uchun ekvivalent misolni ko‘rsatadi:

Misol

SELECT Customers jadvalining dastlabki 3 ta yozuvi:

SELECT * FROM Customers
LIMIT 3;

O‘zingiz sinab ko‘ring »

Oracle - FETCH FIRST bandi

Quyidagi SQL Oracle uchun ekvivalent misolni ko‘rsatadi:

Misol

SELECT Customers jadvalining dastlabki 3 ta yozuvi:

SELECT * FROM Customers
FETCH FIRST 3 ROWS ONLY;

SQL TOP PERCENT Misol

Bu yerda biz foiz sintaksisi bilan SELECT TOP bandidan foydalanamiz.

Quyidagi SQL "Customers" jadvalidagi yozuvlarning birinchi 50% qismini tanlaydi (SQL Server/MS Access uchun):

Misol

SELECT TOP 50 PERCENT * FROM Customers;

O‘zingiz sinab ko‘ring »

Quyidagi SQL Oracle uchun ekvivalent misolni ko‘rsatadi:

Misol

SELECT * FROM Customers
FETCH FIRST 50 PERCENT ROWS ONLY;

SELECT TOP WHERE bilan

Quyidagi SQL "Customers" jadvalidan Country qiymati "Germany" bo‘lgan dastlabki uchta yozuvni tanlaydi (SQL Server/MS Access uchun):

Misol

SELECT TOP 3 * FROM Customers
WHERE Country = 'Germany';

O‘zingiz sinab ko‘ring »

Quyidagi SQL MySQL uchun ekvivalent misolni ko‘rsatadi:

Misol

SELECT * FROM Customers
WHERE Country = 'Germany'
LIMIT 3;

O‘zingiz sinab ko‘ring »

Quyidagi SQL Oracle uchun ekvivalent misolni ko‘rsatadi:

Misol

SELECT * FROM Customers
WHERE Country = 'Germany'
FETCH FIRST 3 ROWS ONLY;

SELECT TOP va ORDER BY

Natijani saralamoqchi bo‘lganingizda ORDER BY kalit so‘zini qo‘shing va saralangan natijaning dastlabki 3 ta yozuvini qaytaring.

SQL Server va MS Access uchun:

Misol

Natijani CustomerName bo‘yicha alifbo tartibida teskari tartiblang va dastlabki 3 ta yozuvni qaytaring:

SELECT TOP 3 * FROM Customers
ORDER BY CustomerName DESC;

O‘zingiz sinab ko‘ring »

Quyidagi SQL MySQL uchun ekvivalent misolni ko‘rsatadi:

Misol

SELECT * FROM Customers
ORDER BY CustomerName DESC
LIMIT 3;

O‘zingiz sinab ko‘ring »

Quyidagi SQL Oracle uchun ekvivalent misolni ko‘rsatadi:

Misol

SELECT * FROM Customers
ORDER BY CustomerName DESC
FETCH FIRST 3 ROWS ONLY;

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