🔍 WHERE shartlari - =, <, >, !=, BETWEEN, LIKE

-- Aniq qiymat qidirish
SELECT * FROM users WHERE age = 25;
SELECT * FROM users WHERE name = 'Ali Valiyev';
SELECT * FROM users WHERE email = '[email protected]';

-- Teng bo'lmagan qiymatlar
SELECT * FROM users WHERE age != 25;
SELECT * FROM users WHERE age <> 25;  -- Bir xil natija
SELECT * FROM users WHERE name != 'Ali Valiyev';

-- 25 dan kichik yosh
SELECT * FROM users WHERE age < 25;

-- Belgili narxdan arzon
SELECT * FROM products WHERE price < 100.0;

-- 25 dan katta yosh
SELECT * FROM users WHERE age > 25;

-- Belgili narxdan qimmat
SELECT * FROM products WHERE price > 50.0;

-- 25 yosh va undan kichik
SELECT * FROM users WHERE age <= 25;

-- 100 dan arzon yoki teng
SELECT * FROM products WHERE price <= 100.0;

-- 25 yosh va undan katta
SELECT * FROM users WHERE age >= 25;

-- 50 dan qimmat yoki teng
SELECT * FROM products WHERE price >= 50.0;

-- 25 va 35 yosh orasida
SELECT * FROM users WHERE age BETWEEN 25 AND 35;

-- 100 va 500 narx orasida
SELECT * FROM products WHERE price BETWEEN 100 AND 500;

-- BETWEEN = >= AND <=
SELECT * FROM users WHERE age >= 25 AND age <= 35;  -- Bir xil natija

-- 'Ali' bilan boshlanadigan
SELECT * FROM users WHERE name LIKE 'Ali%';

-- 'Ali' bilan tugagan
SELECT * FROM users WHERE name LIKE '%Ali';

-- 'Ali' ni o'z ichiga olgan
SELECT * FROM users WHERE name LIKE '%Ali%';

-- 'a' bilan boshlanadigan (katta-kichik harf)
SELECT * FROM users WHERE name LIKE 'a%';

-- 3 harfli ism
SELECT * FROM users WHERE name LIKE '___';

-- 'A' bilan boshlanadigan 4 harfli ism
SELECT * FROM users WHERE name LIKE 'A___';

-- Telefon raqami pattern
SELECT * FROM users WHERE phone LIKE '+998__-___-__-__';

-- Katta-kichik harf farqi
SELECT * FROM users WHERE name LIKE 'ali%';  -- 'ali' bilan boshlanadigan
SELECT * FROM users WHERE name LIKE 'Ali%';  -- 'Ali' bilan boshlanadigan

-- ESCAPE belgisi
SELECT * FROM products WHERE name LIKE '50%';  -- 50% ni qidirish
SELECT * FROM products WHERE name LIKE '50\%' ESCAPE '\';  -- 50% ni qidirish

-- Belgili qiymatlar ro'yxatida
SELECT * FROM users WHERE age IN (25, 30, 35);

-- Belgili ismlar ro'yxatida
SELECT * FROM users WHERE name IN ('Ali', 'Malika', 'Bobur');

-- IN = OR
SELECT * FROM users WHERE age = 25 OR age = 30 OR age = 35;  -- Bir xil natija

-- 25 yosh emas
SELECT * FROM users WHERE age != 25;
SELECT * FROM users WHERE age <> 25;
SELECT * FROM users WHERE NOT age = 25;

-- Belgili ismlar ro'yxatida emas
SELECT * FROM users WHERE name NOT IN ('Ali', 'Malika');

-- Belgili pattern ga mos kelmaydi
SELECT * FROM users WHERE name NOT LIKE 'A%';

-- Oraliqda emas
SELECT * FROM users WHERE age NOT BETWEEN 25 AND 35;

-- NULL qiymatlar
SELECT * FROM users WHERE phone IS NULL;

-- NULL bo'lmagan qiymatlar
SELECT * FROM users WHERE phone IS NOT NULL;

-- Xato: NULL bilan = ishlatish
SELECT * FROM users WHERE phone = NULL;  -- Hech qachon ishlamaydi

-- To'g'ri:
SELECT * FROM users WHERE phone IS NULL;

-- Ikkala shart ham bajarilishi kerak
SELECT * FROM users WHERE age > 25 AND age < 35;
SELECT * FROM users WHERE name LIKE 'A%' AND age > 20;

-- Kamida bitta shart bajarilishi kerak
SELECT * FROM users WHERE age = 25 OR age = 30;
SELECT * FROM users WHERE name LIKE 'A%' OR name LIKE 'M%';

-- Qavs bilan guruhlash
SELECT * FROM users 
WHERE (age > 25 AND age < 35) OR (name LIKE 'A%');

-- Murakkab mantiq
SELECT * FROM products 
WHERE (price > 100 AND category = 'Electronics') 
   OR (price < 50 AND category = 'Books');

-- Jadvallar
CREATE TABLE books (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    title TEXT NOT NULL,
    author TEXT NOT NULL,
    publication_year INTEGER,
    pages INTEGER,
    price REAL,
    category TEXT
);

-- Ma'lumotlar
INSERT INTO books (title, author, publication_year, pages, price, category) VALUES 
('Python Programming', 'John Doe', 2020, 300, 45.99, 'Programming'),
('JavaScript Guide', 'Jane Smith', 2019, 250, 35.50, 'Programming'),
('History of Uzbekistan', 'Ahmad Karimov', 2018, 400, 25.00, 'History'),
('O''zbek tili', 'Malika Toshmatova', 2021, 200, 15.75, 'Language'),
('Data Science', 'Bobur Valiyev', 2022, 350, 55.00, 'Programming');

-- So'rovlar
-- 2020 yildan keyin nashr etilgan kitoblar
SELECT * FROM books WHERE publication_year > 2020;

-- 30 dan qimmat kitoblar
SELECT * FROM books WHERE price > 30;

-- 200-300 sahifa orasidagi kitoblar
SELECT * FROM books WHERE pages BETWEEN 200 AND 300;

-- 'Python' so'zini o'z ichiga olgan kitoblar
SELECT * FROM books WHERE title LIKE '%Python%';

-- 'Programming' kategoriyasi
SELECT * FROM books WHERE category = 'Programming';

-- 2020 yildan keyin va 40 dan qimmat
SELECT * FROM books WHERE publication_year > 2020 AND price > 40;

-- 'O''zbek' yoki 'Uzbekistan' so'zini o'z ichiga olgan
SELECT * FROM books WHERE title LIKE '%O''zbek%' OR title LIKE '%Uzbekistan%';

-- 300 sahifadan ko'p yoki 50 dan qimmat
SELECT * FROM books WHERE pages > 300 OR price > 50;

-- Indeks yaratish
CREATE INDEX idx_books_price ON books(price);
CREATE INDEX idx_books_category ON books(category);
CREATE INDEX idx_books_year ON books(publication_year);

-- Tez ishlaydigan so'rovlar
SELECT * FROM books WHERE price > 30;  -- Indeks ishlatiladi
SELECT * FROM books WHERE category = 'Programming';  -- Indeks ishlatiladi

-- Sekin ishlaydigan so'rovlar
SELECT * FROM books WHERE title LIKE '%Python%';  -- Indeks ishlatilmaydi
SELECT * FROM books WHERE pages > 200 AND price < 50;  -- Murakkab

-- Xato: Mavjud bo'lmagan ustun
SELECT * FROM books WHERE wrong_column = 'value';
-- Xato: no such column: wrong_column

-- Xato: Ma'lumot turi mos kelmaydi
SELECT * FROM books WHERE price = 'not_a_number';
-- Xato: no such column: not_a_number

-- Xato: NULL bilan = ishlatish
SELECT * FROM books WHERE price = NULL;  -- Hech qachon ishlamaydi
-- To'g'ri:
SELECT * FROM books WHERE price IS NULL;