Ma`ruza Ma`lumotlar bazasida rеlyatsion modеl va munosabatlar

Data Manipulation Language

№	DML So’rov	Funktionallik
1	INSERT	Jadvalga ma’lumot qo’shish
2	SELECT	Jadvaldan ma’lumot tanlash
3	DELETE	Jadvaldan ma’lumot o’chirish
4	UPDATE	Jadvaldagi ma’lumotlarni o’zgartirish/yangilash

#2) Data Manipulation Language MB dagi ma’lumotlarga maydon qo’shish/o’zgartirish

SELECT … FROM

Select more than 1 column:
SELECT “COLUMN_NAME_1”, “COLUMN_NAME_2”
FROM “TABLE_NAME”
Select all columns:
SELECT *
FROM “TABLE_NAME”

Ma’lumotlarni tanlashning turli usullari:

Select unique values:
SELECT DISTINCT “Column_Name”
FROM “TABLE_NAME”

WHERE

SELECT “COLUMN_NAME”

FROM “TABLE_NAME”

WHERE “CONDITION”

Vaziyatdan kelib chiqqan holda bizga faqatgina ma’lum bir shart asosida aniq bir maydonni qidiradigan yoki ajratadigan bo’lsak unda “WHERE” so’zini buyruqlarda ishlatish mumkin.
“WHERE” so’zi:
Olinishi rejalashtirilgan ma’lumotlarni filtrlash.
SELECT * FROM employees WHERE Age > 45

Data Control Language

№	DCL So’rov	Funktionallik
1	GRANT	MBdagi ma’lumotlarga ga ulanishga ruxsat berish
2	COMMENT	MB da kommentlar yozish
3	REVOKE	Berilgan ruhsatni qaytarib olish