Savollar: Matematik standart funksiyalar haqida ma’lumot bering

214-17 – guruh talabasi Barotov Mirfayzning Ma’lumotlar Bazasi fanidan Yakuniy Nazorat ish

2-Variant

Savollar:

1. 
   Matematik standart funksiyalar haqida ma’lumot bering.
   
2. 
   EXISTS standart so’zi va uning sintaksisi.
   
3. 
   Uchta jadvalni INNER JOIN orqali birlashtirilsin va har biridan bittadan ustun chiqarilsin.
   

Javoblar:

1 . Ma’lumotlar bazida 20 dan ortiq matematik standart funksiyalar bor. Odatda biz min(),max(), count(), avg() shularni ishlatamiz. Bu funsiyalarni biz har doim Select dan keyin ishlatamiz. Masalan kichik jadval yaratamiz, :

CREATE TABLE "phones" (

"id" INTEGER,

"name" TEXT,

"price" REAL

);

INSERT into phones VALUES

(1,'Iphone 11 64Gb', 800),

(2,'Samsung s20 64Gb', 750),

(3,'Sumsung s20 plus 128Gb',1000),

(4,'Iphone 11 pro 64Gb',1000),

(5,'Mi Note 10 64Gb', 600);

Select *from phones;

1	Iphone 11 64Gb	800.0
2	Samsung s20 64Gb	750.0
3	Sumsung s20 plus 128Gb	1000.0
4	Iphone 11 pro 64Gb	1000.0
5	Mi Note 10 64Gb	600.0

Bizga eng arzon tefon kerak bo’lsa min() standart funksiyadan foydalanamiz:

SELECT name, min(price) as "price" from phones;

Mi Note 10 64Gb

600.0

Bizga eng qimmat telfon kerak bo’lsa, max() standart funksiyadan foydalanamiz: